Spatially modified elastic laminates

ABSTRACT

Microtextured elastomeric laminates comprising at least one elastomeric layer and at least one thin skin layer is preferably prepared by coextrusion of the layers followed by stretching the laminate past the elastic limit of the skin layers in predetermined regions of the laminate and then allowing the laminate to recover in these regions.

FIELD OF THE INVENTION

The invention concerns elastomeric films and more specifically concernsan improved elastomeric laminate.

BACKGROUND

Elastomeric films have for some time been used and discussed in theliterature with regard to their applications in disposable products,such as baby diapers and adult incontinent devices. These elastomericwebs or films are used primarily in the body hugging portions ofgarments. In diapers, for example, elastomeric bands are typically usedin the waistband portions such as discussed in U.S. Pat. No. 4,681,580,issued to Reising et al., and Lash, U.S. Pat. No. 4,710,189. Both ofthese patents describe the use of elastomeric materials which have aheat stable and a heat unstable form. The heat unstable form is createdby stretching the material when heated around its crystalline or secondphase transition temperature followed by a rapid quenching to freeze inthe heat unstable extended form. The heat unstable elastomeric film canthen be applied to the, e.g., diaper and then heated to its heat stableelastomeric form. This will then result in a desirable shirring orgathering of the waistband of the diaper. A problem with thesematerials, other than cost, is the fact that the temperature at whichthe material must be heated to release the heat unstable form is aninherent and essentially unalterable property of the material to beused. This extreme inflexibility can cause severe problems. First, it ismore difficult to engineer the other materials with which the waistbandis associated so that they are compatible with the temperature to whichthe elastomeric member must be heated in order to release the heatunstable form. Frequently this temperature is rather high which canpotentially cause significant problems with the adhesive used to attachthe elastomeric waistband, or, e.g., the protective back sheet or topsheet of the diaper. Further, once chosen the elastomer choice canconstrain the manufacturing process rendering it inflexible to lotvariations, market availability and costs of raw materials (particularlyelastomer(s)), customer demands, etc.

Other materials and methods have been proposed. For example, Burger,U.S. Pat. No. 3,694,815, proposed a method for attaching a stretchedrelaxed elastic ribbon to a garment by stretching conventional elasticribbons and immediately freezing the elastomeric material at relativelyextreme low temperatures (e.g., well below ambient). This process wouldobviously severely constrain the processing conditions and materialswhich could be used when attaching the elastomeric strand to itsbacking. UK Pat. Application 2190406 A proposed maintaining aconventional elastomer in a stretched condition, while attaching it tothe member to be shirred (e.g., a diaper), by a rigidifying member,which would then be removed or destroyed following the attachmentprocedure. As described, the elastomers are first stretched then appliedto the rigidifying member in its stretched form. Finally, Matray et al.,UK Pat. 2,160,473, proposes an elastomer which will shrink at anelevated temperature (e.g., at or above 175° F. or 79.4° C.). Theallegedly novel feature of this material, compared to the heat shrinkmaterials discussed above, is that it does not require preheating duringthe stretching operation but rather could be stretched at ambienttemperatures by a differential speed roll process or by "cold rolling"The polymer proposed was a copolymer having alternating segments ofpolyamidepolyether block polymers, commercially available under thetrade name Pebax, particularly Pebax Extrusion grades 2533 and 3533. Asan alternative, this patent application proposed placing a thinEVA(ethylene vinyl acetate) layer(s) over the elastomer by, e.g.,coextrusion. The skin layer is chosen to prevent blocking or to becompatible with a later applied adhesive. It was noted that this layercan also produce a pleasing hand, but should not interfere with heatshrinkability.

Problems with these elastomeric films include the difficulties inherentin applying a stretched elastic member to a flexible substrate such as adisposable diaper. Although some of the elastomers proposed have theadvantage that they can be applied at ambient conditions in a heatstretched unstable form, subsequent, often extreme, heating is requiredto release the heat unstable form to a contracted heat stable form. Thetemperature of this heat release is generally inflexible as it isdetermined at the molecular level of the elastomer. As such, the othermaterials applied to the elastomer, and the process conditions at whichthe elastomer is used, must be carefully selected to be compatible withthis heating step.

Elastomers also exhibit relatively inflexible stress/straincharacteristics which cannot be chosen independently of the activationtemperature. Materials with a high modulus of elasticity areuncomfortable for the wearer. Problems with a relatively stiff or highmodulus of elasticity material can be exaggerated by the coefficient offriction and necking of the elastomer which can cause the material tobite or grab the wearer.

In copending application Ser. No. 07/438,593, filed Nov. 17, 1989,having a common assignee, there is disclosed an elastomeric laminatehaving at least one elastomeric layer and at least one skin layer whichaddresses the above problems in the art. In addition, the laminate hasextremely useful and novel properties. When cast, or after formation,the elastomeric laminate is substantially inelastic. Elasticity can beimparted to the inelastic laminate by stretching the laminate, by atleast a minimum activation stretch ratio, wherein an elastomericmaterial will form immediately, over time or upon the application ofheat. The method by which the elastomeric material is formed can becontrolled by a variety of means. After the laminate has been convertedto an elastomer, there is formed a novel texture in the skin layer(s)that provides significant advantages to the elastomeric laminate.

Despite the numerous advantages in the materials of the copendingapplication, there is room for improvement for some applications. Inorder to activate the nonelastomeric laminate into a state that willallow it to recover and become elastomeric, the laminate must bestretched a substantial amount for many materials contemplated as usefulfor the skin and core layers. This is problematic for some applicationswhere low activation stretch ratios for the laminate would be desirableor where it is desired to obtain elasticity in specified areas.

The desirability of obtaining elasticity in specified areas of a ribbonor tape-like substrate is illustrated by U.S. Pat. Nos. 3,800,796,4,834,820, 4,778,701 and 4,227,952, which disclose the use of compositematerials designed to have specified areas of elasticity for use indiaper systems. However, these composites require complicatedconstruction mechanisms to bring the diverse elements of the compositetogether and/or special procedures for their manufacture and use thatlimits their general applicability.

SUMMARY OF THE INVENTION

The present invention relates to improved non-tacky, microtextured,multi-layer elastomeric laminates. The laminates of the presentinvention are comprised both of an elastomeric polymeric core layer(s),which provides elastomeric properties to the laminate and one or morepolymeric skin layers, which are capable of becoming microtextured atspecified areas along the laminate length. The microtextured areas willcorrespond to sections of the laminate that have been activated from aninelastic to an elastomeric form. In preferred embodiments of thepresent invention, the skin layer further can function to permitcontrolled recovery of the stretched elastomer, modify the modulusbehavior of the elastomeric laminate and/or stabilize the shape of theelastomeric laminate (e.g., by controlling further necking). Laminatescan be prepared by coextrusion of the selected polymers or byapplication of one or more elastomer layer(s) onto one or more alreadyformed skin layer(s). Coextrusion is preferred. The novel, non-tackymicrotextured laminate is obtained by stretching the laminate past theelastic limit of predetermined regions of the skin layers. This istermed selective or preferential activation. The laminate then recoversin these predetermined regions, which can be instantaneous, over anextended time period, which is skin layer controllable, or by theapplication of heat, which is also skin layer controllable.

This selective or preferential activation is produced by controlling therelative elastic modulus values of selected cross-sectional areas of thelaminate to be less than modulus values of adjacent cross-sectionalareas. The areas controlled to have reduced modulus will preferentiallyyield when subjected to stress. This will result in either preferentialelastization of specified zones or fully elasticized laminates withhigher strain regions, depending on the location of the areas of lowmodulus and the manner of stretch. Alternatively, the laminate could betreated to enhance or concentrate stress in selected regions. This willyield essentially the same results as providing low modulus regions. Byeither construction, the laminate can activate in selected regions atlower stretch ratios than would normally be required to activate theentire laminate.

The modulus can be controlled by providing one or more layers of thelaminate with relatively low and high modulus areas. This can beaccomplished by selectively altering the physical or chemicalcharacteristics of regions of one or more layers or by providing alayer(s) with regions of diverse chemical composition. Regionallyenhanced stress can be induced by physical or chemical treatment of alayer(s) such as by ablation, scoring, corona treatment or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional segment of an extruded laminate of theinvention before microstructuring.

FIG. 2 is the cross-sectional segment of FIG. 1 of the laminate withmicrostructuring caused by uniaxially stretching a film of theinvention.

FIG. 3 is a schematic representation of a process and apparatus used tocoextrude the laminates of the invention.

FIG. 4 is a diagram showing the stress-strain characteristics of alaminate and its component layers.

FIG. 5 shows an electron micrograph (1000×) of a laminate sample with apolyethylene skin which was simultaneously biaxially stretched.

FIG. 6 is a photograph of a unstretched laminate that has been markedwith ink.

FIG. 7 is a photograph of the stretched laminate of FIG. 6 marked withthe same ink.

FIG. 8 (T-N) are stress/strain curves for a series of laminate films.

FIG. 9 is a scanning electron micrograph (100×) of the surface of alaminate which has been sequentially biaxially stretched.

FIG. 10 is a scanning electron micrograph (100×) of a simultaneouslybiaxially stretched invention laminate which has a polypropylene skin.

FIG. 11 is a diagram showing the relationship between the shrinkmechanism and the core/skin ratio and stretch ratio for a seconduniaxially stretched film.

FIG. 12 is a diagram showing the relationship between the core/skinratio, the percent of total recovery and activation temperature.

FIG. 13 is a schematic representation of a series of laminates annealed0, 25%, 50%, 75% and 100%, respectively.

FIGS. 14 (A)-(C) are a series of stress-strain curves for the samplesschematically shown in FIG. 13 for 25%, 50% and 75% annealing,respectively.

FIGS. 15 (A)-(C) are light micrographs of a 25% annealed sample of FIG.13 as cast, stretched and relaxed, respectively.

FIG. 16 is a light micrograph of a relaxed sample annealed with aregular repeating diamond pattern.

FIG. 17 is a diaper tape tab formed of the invention preferentiallyactivatable laminate.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The present invention relates broadly to novel non-tacky, multi-layerelastomeric laminates comprising at least one elastomeric layer and atleast one relatively nonelastomeric skin layer. The selected regions ofthe skin layer are stretched beyond their elastic limit and relaxed withthe core so as to form an elastic region having a microstructured skinlayer. Microstructure means that the layer contains peak and valleyirregularities or folds which are large enough to be perceived by theunaided human eye as causing increased opacity over the opacity of thelaminate before microstructuring, and which irregularities are smallenough to be perceived as smooth or soft to human skin. Magnification ofthe irregularities is required to see the details of the microstructuredtexture.

The elastomer can broadly include any material which is capable of beingformed into a thin film layer and exhibits elastomeric properties atambient conditions. Elastomeric means that the material willsubstantially resume its original shape after being stretched. Further,preferably, the elastomer will sustain only small permanent setfollowing deformation and relaxation which set is preferably less than20 percent and more preferably less than 10 percent of the originallength at moderate elongation, e.g., about 400-500%. Generally, anyelastomer is acceptable which is capable of being stretched to a degreethat causes relatively consistent permanent deformation in a relativelyinelastic skin layer. This can be as low as 50% elongation. Preferably,however, the elastomer is capable of undergoing up to 300 to 1200%elongation at room temperature, and most preferably up to 600 to 800%elongation at room temperature. The elastomer can be both pureelastomers and blends with an elastomeric phase or content that willstill exhibit substantial elastomeric properties at room temperature.

As discussed above, heat-shrinkable elastics have received considerableattention due to the ability to fabricate a product using the unstablestretched elastomer at ambient conditions and then later applying heatto shirr the product. Although these elastomers are contemplated for usein the present invention, other non-heat-shrinkable elastomers can beused while retaining the advantages of heat shrinkability with the addeddimension of the possibility of substantially controlling the heatshrink process. Non-heat-shrinkable means that the elastomer, whenstretched, will substantially recover sustaining only a small permanentset as discussed above. Therefore, the elastomeric layer can be formedfrom non-heat-shrinkable polymers such as block copolymers which areelastomeric such as those known to those skilled in the art as A-B orA-B-A block copolymers. These block copolymers are described, forexample, in U.S. Pat. Nos. 3,265,765; 3,562,356; 3,700,633; 4,116,917and 4,156,673, the substance of which are incorporated herein byreference. Styrene/isoprene, butadiene or ethylene-butylene/styrene(SIS, SBS or SEBS) block copolymers are particularly useful. Otheruseful elastomeric compositions can include elastomeric polyurethanes,ethylene copolymers such as ethylene vinyl acetates, ethylene/propylenecopolymer elastomers or ethylene/propylene/diene terpolymer elastomers.Blends of these elastomers with each other or with modifyingnon-elastomers are also contemplated. For example, up to 50 weightpercent, but preferably less than 30 weight percent, of polymers can beadded as stiffening aids such as polyvinylstyrenes, polystyrenes such aspoly(alpha-methyl)styrene, polyesters, epoxies, polyolefins, e.g.,polyethylene or certain ethylene vinyl acetates, preferably those ofhigher molecular weight, or coumarone-indene resin. The ability to usethese types of elastomers and blends provides the invention laminatewith significant flexibility.

Viscosity reducing polymers and plasticizers can also be blended withthe elastomers such as low molecular weight polyethylene andpolypropylene polymers and copolymers, or tackifying resins such asWingtack™, aliphatic hydrocarbon tackifiers available from GoodyearChemical Company. Tackifiers can also be used to increase theadhesiveness of an elastomeric layer to a skin layer. Examples oftackifiers include aliphatic or aromatic hydrocarbon liquid tackifiers,polyterpene resin tackifiers, and hydrogenated tackifying resins.Aliphatic hydrocarbon resins are preferred.

Additives such as dyes, pigments, antioxidants, antistatic agents,bonding aids, antiblocking agents, slip agents, heat stabilizers,photostabilizers, foaming agents, glass bubbles, starch and metal saltsfor degradability or microfibers can also be used in the elastomericcore layer(s). Suitable antistatic aids include ethoxylated amines orquaternary amines such as those described, for example, in U.S. Pat. No.4,386,125 (Shiraki), who also describes suitable antiblocking agents,slip agents and lubricants. Softening agents, tackifiers or lubricantsare described, for example, in U.S. Pat. No. 4,813,947 (Korpman) andinclude coumarone-indene resins, terpene resins, hydrocarbon resins andthe like. These agents can also function as viscosity reducing aids.Conventional heat stabilizers include organic phosphates, trihydroxybutyrophenone or zinc salts of alkyl dithiocarbonate. Suitableantioxidants include hindered phenolic compounds and amines possiblywith thiodipropionic acid or aromatic phosphates or tertiary butylcresol, see also U.S. Pat. No. 4,476,180 (Wnuk) for suitable additivesand percentages.

Short fibers or microfibers can be used to reinforce the elastomericlayer for certain applications. These fibers are well known and includepolymeric fibers, mineral wool, glass fibers, carbon fibers, silicatefibers and the like. Further, certain particles can be used, includingcarbon and pigments.

Glass bubbles or foaming agents are used to lower the density of theelastomeric layer and can be used to reduce cost by decreasing theelastomer content required. These agents can also be used to increasethe bulk of the elastomer. Suitable glass bubbles are described in U.S.Pat. Nos. 4,767,726 and 3,365,315. Foaming agents used to generatebubbles in the elastomer include azodicarbonamides. Fillers can also beused to some extent to reduce costs. Fillers, which can also function asantiblocking agents, include titanium dioxide and calcium carbonate.

The skin layer can be formed of any semi-crystalline or amorphouspolymer that is less elastic than the core layer(s) and will undergopermanent deformation at the stretch percentage that the elastomericlaminate will undergo. Therefore, slightly elastic compounds, such assome olefinic elastomers, e.g. ethylene-propylene elastomers orethylene-propylene-diene terpolymer elastomers or ethylenic copolymers,e.g., ethylene vinyl acetate, can be used as skin layers, either aloneor in blends. However, the skin layer is generally a polyolefin such aspolyethylene, polypropylene, polybutylene or apolyethylene-polypropylene copolymer, but may also be wholly or partlypolyamide such as nylon, polyester such as polyethylene terephthalate,polyvinylidene fluoride, polyacrylate such as poly(methylmethacrylate)(only in blends) and the like, and blends thereof. The skinlayer material can be influenced by the type of elastomer selected. Ifthe elastomeric layer is in direct contact with the skin layer the skinlayer should have sufficient adhesion to the elastomeric core layer suchthat it will not readily delaminate. Acceptable skin-to-core contact hasbeen found to follow three modes; first, full contact between core andmicrotextured skin; second, cohesive failure of the core under themicrostructure folds; and third, adhesive failure of the skin to thecore under the microstructure folds with intermittent skin/core contactat the fold valleys. However, where a high modulus elastomeric layer isused with a softer polymer skin layer attachment may be acceptable yet amicrotextured surface may not form.

The skin layer is used in conjunction with an elastomeric layer and caneither be an outer layer or an inner layer (e.g., sandwiched between twoelastomeric layers). Used as either an outer or inner layer, the skinlayer will modify the elastic properties of the elastomeric laminate.

Additives useful in the skin layer include, but are not limited to,mineral oil extenders, antistatic agents, pigments, dyes, antiblockingagents, provided in amounts less than about 15%, starch and metal saltsfor degradability and stabilizers such as those described for theelastomeric core layer.

Other layers may be added between the core layer and the outer layers,such as tie layers to improve the bonding of the layers. Tie layers canbe formed of, or compounded with, typical compounds for this useincluding maleic anhydride modified elastomers, ethyl vinyl acetates andolefins, polyacrylic imides, butyl acrylates, peroxides such asperoxypolymers, e.g., peroxyolefins, silanes, e.g., epoxysilanes,reactive polystyrenes, chlorinated polyethylene, acrylic acid modifiedpolyolefins and ethyl vinyl acetates with acetate and anhydridefunctional groups and the like, which can also be used in blends or ascompatiblizers in one or more of the skin or core layers. Tie layers areparticularly useful when the bonding force between the skin and core islow. This is often the case with polyethylene skin as its low surfacetension resists adhesion. However, any added layers must notsignificantly affect the microstructuring of the skin layers.

One unique feature of the invention is the ability to control the shrinkrecovery mechanism of the laminate depending on the conditions of filmformation, the nature of the elastomeric layer(s), the nature of theskin layer(s), the manner in which the laminate film is stretched andthe relative thicknesses of the elastomeric and skin layer(s). Bycontrolling these variables in accordance with the teaching of thisinvention, the laminate film can be designed to instantaneously recover,recover over time or recover upon heat activation.

A laminate capable of instantaneous shrink is one in which the stretchedportion of the elastomeric laminate will recover more than 15% in 1 sec.A laminate capable of time shrink is one where the 15% recovery pointtakes place more than 1 sec., preferably more than 5 sec., mostpreferably more than 20 sec. after stretch, and a laminate capable ofheat shrink is where less than 15% shrink recovery occurs to thelaminate in the first 20 seconds after stretch. Percent recovery is thepercent that the amount of shrinkage is of the stretched length minusthe original length of the activated area. For heat shrink there will bean activation temperature which will initiate significant heat activatedrecovery. The activation temperature used for heat shrink will generallybe the temperature that will yield 50% of the total possible recovery(T_(a-50)) and preferably this temperature is defined as the temperaturewhich will yield 90% (T_(a-90)) of the total possible recovery. Totalpossible recovery includes the amount of preactivation shrinkage.

Generally, where the skin layer of the laminate in the preferentialactivation region is relatively thin, the laminate will tend to contractor recover immediately. When the skin thickness is increasedsufficiently the laminate can become heat shrinkable in the activatedregions. This phenomenon can occur even when the elastomeric layer isformed from a non-heat shrinkable material. By careful selection of thethicknesses of the elastomeric layer and the skin layer(s), thetemperature at which the laminate recovers by a set amount can becontrolled within a set range. This is termed skin controlled recovery,where generally by altering the thickness or composition of the skin,one can raise the elastic recovery activation temperature of anelastomeric core by a significant degree, generally more than at least10° F. (5.6° C.) and preferably by 15° F. (8.3° C.) and more. Althoughany skin thickness which is effective can be employed, too thick a skinwill cause the laminate to remain permanently set when stretched.Generally, where a single skin is less than 30% of the laminate thiswill not occur. For most heat or time shrink materials, the stretchedactivated regions of the elastomeric laminate must be cooled so that theenergy released during stretching does not cause immediate heatactivated elastic recovery. Fine tuning of the shrink recovery mechanismcan be accomplished by the degree that the activated regions arestretched. However, where it is desired to significantly stretch thepreferentially activated regions, the adjacent nonpreferentiallyactivated regions must have a Youngs Modulus greater than theinstantaneous modulus of the activated region at the degree of desiredstretch.

This overall control over the shrink recovery mechanism of the activatedregions of the elastomeric laminate discussed above coupled with theability to control the amount of stretch needed to activate regions ofthe laminate are extremely important advantages. This control permitsadjustment of the activation and recovery mechanism of the elastomericlaminate to fit the requirements of a manufacturing process, therebyavoiding the need to adjust a manufacturing process to fit the shrinkrecovery mechanism of an elastomer.

One is also able to use skin controlled recovery to control the slow ortime shrink recovery mechanism, as with the heat shrink mechanism. Thisshrink recovery mechanism occurs as an intermediate between instant andheat shrink recovery. Skin layer and stretch ratio control is possibleas in the heat shrink mechanism, with the added ability to change theshrink mechanism in either direction, i.e., toward a heat or an instantshrink elastomeric laminate.

A time shrink recovery laminate will also exhibit some heat shrinkcharacteristics and vice versa. For example, a time shrink laminate canbe prematurely recovered by exposure to heat, e.g., at a time prior to20 seconds after stretch.

Recovery can also be initiated for most time shrink and some lowactivation temperature heat shrink recovery laminates by mechanicaldeformation or activation. In this case, the laminate is scored, folded,wrinkled, or the like to cause localized stress fractures that causelocalized premature folding of the skin, accelerating formation of therecovered microtextured laminate. Mechanical activation can be performedby any suitable method such as by using a textured roll, a scoringwheel, mechanical deformation or the like.

FIG. 11 shows a shrink mechanism diagram forpolypropylene/styrene-isoprene-styrene (SIS)/polypropylene(PP) laminatesprepared in accordance with Example 27. This diagram demonstrates theability to control the shrink recovery mechanism by the skin/core ratioand the stretch ratio.

Although FIG. 11 is illustrative of a particular set of startingmaterials and thicknesses it does represent the general relationshipbetween the layer ratios and stretch ratio to the shrink mechanism ofthe laminate. Other variables will affect the above relationship such asoverall laminate thickness, the presence of tie layers and the thicknessand type of any adhesive layer. However, the general relationshipbetween the core/skin ratio and the stretch ratio to the relaxationmethod will still be present.

Additives to the core layer discussed above can significantly affect theshrink recovery mechanism. For example, stiffening aids such aspolystyrene can shift an otherwise heat shrinkable laminate into a timeor instant shrink laminate. However, the addition of polypropylene orlinear low density polyethylene (less than 15%) to astyrene/isoprene/styrene block copolymer core resulted in exactly theopposite effect, namely transforming time or instant shrink laminates toheat shrink or no shrink laminates. However, the possibility ofpolyolefin use in the elastomeric core layer is significant from aprocessing standpoint in permitting limited recycling of off batcheswhile polyolefin additives can lower extruder torque. These additivesare also useful in providing the invention low modulus regions when theyare selectively included in either these regions, or the adjoining highmodulus regions, depending on the modulus effect of the additive.

A further unique feature of the present invention lies in the ability tosignificantly reduce the coefficient of friction (C.O.F.) of theactivated regions of the elastomeric laminate. The microtexturing is themajor factor contributing to this C.O.F. reduction which, as discussedabove, is controllable not only by the manner in which the laminate isstretched but also by the degree of stretch, the overall laminatethickness, the laminate layer composition and the core to skin ratio.Fine texture yields lower C.O.F. values. Preferably, the C.O.F. will bereduced by a factor of 0.5 and most preferably by at least a factor of0.1 of the microtextured laminate to itself in the direction of stretch,when a microstructured surface is formed in accordance with theinvention, as compared to the as cast laminate. This ability to reduceC.O.F. is extremely advantageous as it contributes to a softer textureand feel for the laminate, which is desirable for use in the medical andapparel fields.

Writability of the laminate in the activated regions is also increasedby the microstructured surface that results when the stretched laminaterecovers. Either organic solvent or water-based inks will tend to flowinto the microstructured surface channels and dry there. FIG. 6 showsthe surface of an unstretched, untextured laminate where the ink clearlybeads up. FIG. 7 demonstrates the improvement in writability for thelaminate of FIG. 6 after stretching and recovery to create amicrotextured surface (see example 24). The more viscous the ink theless it will tend to wick in the microchannels of the surface and hencebleed. Similarly, the more the surface attraction between the skin layerand the ink, the better will be the writing characteristics of themicrostructured surface. The writing surface characteristics of the filmcan also be altered with conventional additive or surface treatmenttechniques to the extent that they do not interfere with microtexturing.

The improvements in the laminate structure of this invention over thatof copending application Ser. No. 07/438,593 lie in the control of theelastic modulus or stress at selected regions or zones of the laminatecross-section. First, the zones or regions controlled to have loweroverall modulus values will preferentially yield before adjacent, in thedirection of an orienting stress, higher modulus regions. This moduluscontrol can be accomplished by a variety of methods that can involve theprelaminate formation stages, the formation stage, or post formationtreatment of a particular laminate or laminate intermediate.

Similarly, localization of stress, applied to the whole laminate, canresult in preferential elongation in areas containing these localizedstress regions. This stress control can also be effected by a variety ofmethods in any of a multitude of stages in the formation of thelaminate.

Post laminate-formation modulus or stress treatment has the advantage ofpermitting modification of laminates without having to modify theapparatus that produces the basic material. The same line can producelaminates having relatively constant modulus values over itscross-section, or laminates for later treatment to yield regions ofmodified modulus or stress values. This post laminate formation modulustreatment can include post formation annealing, selective crosslinkingor selective plasticization. Post formation stress localization can beeffected by localized corona treatment, mechanical ablation, scoring,cutting out laminate material, indentation, controlled localizedstretching or like treatments.

In corona treatment, the treatment is allowed to progress to the pointof saturation by variation of the power density and/or time of exposure.At the point of saturation, the degree of oxidation of the surface doesnot further increase, and further treatment results in ablation of thesurface. Corona treatment can be selectively applied by use of masks.The point of saturation can be reached more readily by raising thetemperature of the laminate to be treated. The temperature of thelaminate can be raised even above the glass transition point of one ormore layers, as any annealing effects will be non-preferential. This hasadvantages in the final product as annealing relieves localized stressesat the layer interfaces. This improves product stability, as stress canaccelerate degradation of some elastomers as well as delamination.

Lower power corona treatment without ablation is also possible. In thiscase, the laminate would be treated below the saturation point. Thepreferential stress regions would be formed by changing the takeoffangle from, e.g., the corona treatment take-up roll or surface. A sharptakeup angle will create microcracks in the material surface where ithas been corona treated. Generally, an angle of 110° or greater fromnormal is sufficient. This will create an area of preferential stress.Preferably, this would be accomplished by corona treating longitudinalzones (in the machine direction), which when subjected to a sharp takeupangle would create alternating zones with and without microcracks.

Annealing can be performed at any suitable temperature and for anysuitable duration, depending on the material to be modified. Generally,this temperature is above the glass transition temperature of the skinlayer material. If heated above the melt temperature of the skin layer,it can be cooled at a rate that will either induce more or lesscrystallization than than the adjacent regions to create eitherpreferential or nonpreferential activation regions. Specific preferredannealing temperatures will depend upon the amount of crystallinityalready present in the material and the material itself. To work themodulus or stress modification, treatment method should be capable offorming a laminate which under, e.g., elongational stress will exhibit adouble yield point, such as that shown in FIG. 14(A). In this figure,the first yield point DD corresponds to the initiation of elongationalorientation in the low modulus region(s) or zone(s), whereas the secondyield point EE corresponds to the start of elongational orientation inthe higher modulus region(s) or zones. This double yield point isessential for good regionalized, modulus controlled, elastic activationof the laminate. The greater the separation between the two yieldpoints, the more accurate will be the ability to control regionalizedorientation and elastic activation. Greater yield point separation alsopermits higher elongation ratios in the lower modulus region(s) prior tothe initiation of secondary stretching in the higher modulus region.This double yield point is not as essential when a patterned array oflow modulus or stress areas are used to create a complex compositesurface structure. In this case, a great, if not infinite, number ofyield points may be present as modulus values may fluctuate greatlytransverse to the direction of stretch.

With post formation annealing, the different modulus regions areobtained by taking advantage of the different crystallization states ofparticular polymers, which can be activated by a temperature controlledannealing. Generally, one is capable of annealing semicrystallinepolymers to yield regions having significantly different modulus values,and if the regions are properly oriented to the elongation direction, adouble yield point. Annealing can result in a change in the degree ofcrystallization, the size and arrangement of crystallites, structuralmorphology, and/or the number of tie chains between crystallites, whichchanges have an effect on the elastic modulus of the polymer. With postformation annealing the temperature of effective annealing is generallysignificantly above the glass transition temperature. Material that hasbeen extruded and cast onto a chill roll will generally have a certaindegree of crystallinity, depending on the chill roll temperature,orientation, drawdown, extrusion temperature and the like. In order toinduce additional annealing, the temperature will generally be at least5° C. above T_(g) and at least 50° C. above T_(g) for certain polymerssuch as polypropylene. Higher annealing temperatures will generally bepreferred as this will keep the time of annealing down and willgenerally promote more significant changes in crystallinity.

Annealing or crystallization can also be performed during the formationof the laminate. For example, where extrusion onto a casting wheel isused to form the laminate, the casting wheel can have zones at differenttemperatures to form a laminate with multiple crystalline states.Analogous annealing steps could be used in other extrusion or laminateforming processes.

Annealing can also be performed on specified layers. For example, thetemperature and time of contact with an annealing roll, or the like, canbe controlled to limit the annealing to specified layers. Also annealingcan be performed to a specified layer, or layers, which are then joinedto other layers, such as in a sequential extrusion or laminationprocess.

Polymers suitable for use in forming the respective skin and/or corelayers of the invention elastomeric laminate are generally suitable forannealing treatment as above described, including polyolefins such aspolypropylene or polybutylene, nylon, semicrystalline polyesters such aspolyethyleneterephthalate, polybutyleneterephthalate orpolyethylenenaphthalate or polyvinyl idene fluoride.

FIG. 13 shows a series of annealed structures formed in accordance withthe invention having varying percentages of annealed surface. FIGS. 14(A)-(C) are tensile strength versus strain plots for the annealedstructures shown in FIG. 13(the darker shaded areas indicate theannealed areas). In FIG. 14(A), there are five distinct zones of elasticbehavior of the laminate as it is stretched transverse to the annealedstripes. Zone J corresponds to elastic deformation in the non-annealedregions. Zone K corresponds to the initiation of plastic deformation inthe non-annealed regions. Zone L corresponds to continued orientation inthe non-annealed regions and elastic deformation in the annealedregions. Zone M corresponds to the initiation of plastic deformation inthe annealed region, and Zone Q corresponds to orientation of the entirelaminate. Points DD and EE, as discussed above, are transitional pointsbetween elastic and plastic deformation for the non-annealed andannealed regions, respectively. Similar plots, FIGS. 14(B) and (C), weremade for the 50% and 75% annealed structures of FIG. 13, where DD and EEdesignate identical transition points. These points are not thatdistinct, it is believed, due to heat migration from the annealed tonon-annealed regions resulting in slight transitional, slightly annealedzones. These transition zones reduce the sharpness of the plottedtransition points.

The formed laminate, or an intermediate layer(ed) structure, can also betreated with suitable plasticizing agents to selectively soften certainregions of specified skin or core layers. This will generally lower themodulus in those regions treated, which again will allow for thegeneration of a double yield point laminate. Generally, any plasticizerthat will soften a specified layer will be minimally functional at somelevel. Plasticizers suitable for specified polymers are generally wellknown and are contemplated for use in the present invention. Theplasticizer can be applied to specified regions by any suitable coatingtechnique including rotogravure, extrusion coating, spray coating, Meyerbar coating or any other conventional method. The plasticizer, however,should not significantly migrate from the coating area or zoneresolution will be lost.

The formed laminate, or an intermediate layer or layers, can also besubjected to suitable crosslinking treatment to allow for the stiffeningof selected regions of a laminate. Crosslinking can be initiated by anysuitable method such as chemical, heat or radiation. Photoinitiatorsinclude benzoin ethers, benzyl dialkyl ketals such as2,2-dimethoxy-2-phenylacetophenone, benzophenones and acetophenonederivatives such as 2,2-diethoxyacetophenone, for example. Generally,curing agents need to be introduced into the layer(s) to be crosslinked,either before or during the crosslinking. For example, for radiationcrosslinking the crosslinking agent can be introduced into the layerprior to, e.g., extrusion, then subjecting that layer to selectiveradiation curing, e.g., by selectively irradiating certain specifiedareas of the laminate with the proper type and amount of radiation. Thisirradiation process can likewise be performed during laminate formationas discussed above with regard to plasticization. Crosslinking agentscan also be introduced after the layer is formed, e.g., by topicalapplication (e.g., with solvent carriers) or in selective regions of thelaminate by any suitable method (e.g., the strip coextrusion methoddiscussed herein).

The formed film can also be modified by on-line regionalized heating,followed immediately by stretch activation before the laminate hascooled. In this case the laminate will yield first at the heated areas,where the high temperature has softened and hence temporarily decreasedthe material's elastic modulus. This will be the opposite effect that isgenerally achieved when annealing occurs, i.e., where the heated regionsare allowed to cool. With annealing, the heat releases stresses andinduced orientation. This generally allows a more crystalline andstiffer polymer to form. These annealed areas will then preferentiallyresist yielding when placed under stress.

The regionalized modulus modifications can also be built into thelaminate by strip coextrusion of a layer or layers. By stripcoextrusion, it is meant that a single layer can be formed from aplurality of polymer streams extruded to form multiple regions havingvarying modulus values. Additives can be used to later adjust a region'smodulus value (e.g., crosslinking agents). This multiple component orcomposite layer can then be joined with another layer or layers, whichmay, or may not, similarly be strip coextruded. A preferred mechanismfor strip extrusion is shown in FIG. 3 where D, D' and D" are amultilayer feedblocks or manifolds, such as that disclosed in U.S. Pat.No. 3,557,265 (Chisholm). This multilayer feedblock forms the stripextruded layer and may be used with transition pieces to vary the heightand width of the strip extruded layer or film. E is a conventionalmultiple layer die or a combining adapter and die such as disclosed inU.S. Pat. Nos. 4,152,387 or 4,197,069 (Cloeren). As shown, multilayerfeedblocks or manifolds can be used to feed into each layer passagewayof the multiple layer die E or to only a single passageway of such adie. Depending on the manifold D arrangement, there can be two or morestrips, of different composition, in each layer. Generally, twoalternating strips are fed by the multilayer feedblock. However, morethan two strips can be formed by using a feedblock such as thatdisclosed in Weisner et al., U.S. Pat. No. 4,435,141 (three alternatingstrips). AA, BB, and CC are extruders. AA', BB' and CC' are streams ofthermoplastic material flowing into the feedblock or manifold die. E isthe 3 or more (e.g., 5-layer) layer feedblock and die, F is a heatedcasting roll, and G and H are rolls to facilitate take-off and roll-upof the laminate.

The die and feedblock used are typically heated to facilitate polymerflow and layer adhesion. The temperature of the die depends upon thepolymers employed and the subsequent treatment steps, if any. Generallythe temperature of the die is not critical but temperatures aregenerally in the range of 350° to 550° F. (176.7° to 287.8° C.) with thepolymers exemplified.

Using the Weisner et al. arrangement, it is possible to obtain alaminate layer having up to three separate modulus regions. For amultilayered laminate, each layer can similarly be formed of strips ofmaterials with different potential modulus values, which is shown for athree layer laminate in FIG. 1.

In FIG. 1, numbers 10-18 each represent a separate strip which may ormay not be the same and may or may not be overlapping. For a three layerembodiment outer layers 2 and 3, with strips 10-12 and 16-18, arepreferably skin layers. Each of the strips may be formed of anypotential skin material which are selected to provide for distinctmodulus values in selected regions of the overall laminate.Alternatively, additives can be added to adjust the modulus of a polymerfed as one strip in the feed manifold, which polymer may or may not bethe same as the polymer of adjacent strips. This would include additivessuch as stiffening aids, e.g., polystyrene; softening aids, e.g,plasticizers; fillers; or post fabrication modifiers such ascrosslinking agents. These additives can be used to modify selectedstrips of a skin or core layer while allowing the polymer matrix of thelayer as a whole to remain the same. This approach helps minimizepossible strip separation or a need for compatabilizers, as compared towhere the materials fed to adjacent strips are incompatible polymers.

Core layers(strips 13-15) can be formed of strips of elastic materialhaving different modulus values to yield a laminate with regions ofvarying modulus values. Alternatively, the core can be formed ofalternating strips of elastic material and higher modulus inelasticmaterial. This is preferred in terms of cost. However, the strips mayseparate when stretched if the elastic and inelastic materials aresignificantly incompatible.

Concentration of stress at localized regions within a laminate can beaccomplished in any of a number of ways as previously outlined. Theregions which have been treated to concentrate stress will act asinitiation points for strain elongation. For example, a stressedlaminate will preferentially yield at the point where scored. In orderto create preferential elongation over a entire area of the laminate,preferentially the area will contain regions with numerous score lines.Generally, the higher the concentration of score lines in an area orregion the more precise will be the preferential elongation in that areaor region. Similarly, with other methods such as ablation or coronadischarge, the more concentrated and defined the treatment the moreaccurate will be the preferential elongation.

The overall laminate or prelaminate structure of the present inventionmay be formed by any convenient layer forming process such as bypressing layers together, coextruding the layers or stepwise extrusionof layers, but coextrusion is the presently preferred process forforming a laminate with most modulus modification treatment methodscontemplated. However, modulus modification treatment methods whichdirectly treat middle laminate layers cannot be used with a directcoextrusion method. Coextrusion per se is known and is described, forexample, in U.S. Pat. Nos. 3,557,265 to Chisholm et al. and 3,479,425 toLefevre et al. Tubular coextrusion or double bubble extrusion is alsopossible. The layers are typically coextruded through a specialized dieand/or feedblock that will bring the diverse materials into contactwhile forming the laminate.

Whether the laminate is prepared by coating, lamination, sequentialextrusion, coextrusion or a combination thereof, the laminate formed andits layers will preferably have substantially uniform thicknesses acrossthe laminate. Laminates prepared in this manner have generally uniformproperties with a minimum of edge effects such as curl, modulus change,fraying and the like.

The laminate of the invention has an unlimited range of potentialwidths, the width limited solely by the fabricating machinery widthlimitations. This allows fabrication of zone activatable microtexturedelastomeric laminates for a wide variety of potential uses.

After forming the zone activatable laminate, the laminate is stretchedpast the elastic limit of the skin layer(s) exclusively or preferably inthe lower modulus or preferred stress regions, which deform. The zoneactivated laminate then is recovered instantaneously, with time or bythe application of heat, as discussed above. For heat activated recoverythe inherent temperature of heat activation is determined by thematerials used to form the elastic layer of the laminate in the firstinstance. However, for any particular laminate the activationtemperature, for example, either T_(a-50) or T_(a-90') can be adjustedby varying the skin/core ratio of the laminate, adjusting the percentstretch or the overall laminate thickness. The activation temperatureused for a heat shrink laminate is generally at least 80° F. (26.7° C.),preferably at least 90° F. (32.2° C.) and most preferably over 100° F.(37.8° C.). When heat activated the stretched laminates are quenched ona cooling roller, which prevents the heat generated during elongationfrom prematurely activating laminate recovery in the activated regions.The chill roll temperature is maintained below the activationtemperature.

FIG. 2 is a schematic diagram of the common dimensions which arevariable for uniaxially stretched and recovered laminates in theactivated regions. The general texture is a series of regular repeatingfolds. These variables are the total height A--A', the peak to peakdistance B--B' and the peak to valley distance C--C'. These variableswere measured for a series ofpolyolefin/styrene-isoprene-styrene/polyolefin laminates. General rangesfor A--A', B-B' and C--C' were noted. For total height (A--A') the rangemeasured was from 0.79 to 32 mils (0.02 to 0.81 mm). For peak to peakdistance (B--B'), or the fold period, the measured range was from 0.79to 11.8 mils (0.02 to 0.30 mm). For peak to valley distance (C--C') themeasured range was from 0.04 to 19.7 mils (0.001 to 0.5 mm). Theseranges are only exemplary of the surface characteristics obtainable bythe practice of the present invention. Laminates of other compositionswill demonstrate different microstructures and microstructuredimensions. It is also possible to obtain dimensions outside the aboveranges by suitable selection of core/skin ratios, thicknesses, stretchratios and layer compositions.

Activation will generally be accomplished by stretching the laminate ina direction substantially transverse to a primary extent of the filmhaving at least displaced zones or regions of differing modulus orstress characteristics. These zones can be comprised of a singleuniform, e.g., modulus region or multiple regions of differing modulusvalues yielding an overall zone composite modulus value. This compositevalue will depend upon the arrangement and placement of the low and highmodulus regions of which it is comprised. For a given film, the highmodulus regions can comprise a continuous matrix (in the direction ofstretch), in which are found low modulus regions, or be disperseddistinct regions in a low modulus matrix. Where the high moduluslaminate regions comprise a continuous matrix, the film when stretchedwill exhibit constant strain across the extent(s) transverse to theelongation direction as per

    σ.sub.hi =σ.sub.Li                             (1)

where σ_(hi) the instantaneous strain in the high modulus regions alongthis extent and σ_(Li) is the instantaneous low modulus region strain.Further the instantaneous total Young's Modulus (e_(Ti)) can generallybe described as following equation (2).

    e.sub.Ti =e.sub.h f.sub.h +e.sub.L f.sub.L                 (2)

where

    f.sub.h +f.sub.L =1                                        (3)

    π.sub.T =π.sub.h f.sub.h +π.sub.L f.sub.L         (4)

f is the volume fraction of a particular modulus region, π designatesthe stress and e is the composite modulus for the extent. The extent(s)with the lowest modulus value(s) will preferentially yield first, untilits stress value overcomes the yield point of the extent(s) with thenext highest modulus and so on.

Where the laminate has a continuous low modulus region in the directionof stress, the elongation will propagate preferentially in these lowmodulus regions. Stress, however, should remain constant as per equation(5).

    π.sub.h =π.sub.L =π.sub.T                         (5)

while

    σ.sub.T =σ.sub.h f.sub.h +σ.sub.L f.sub.L (6)

Equation (2) will still apply. This indicates that stress will remainconstant across a given transverse cross-section. However, within thatcross-section, as the modulus value will vary with the material (e_(m))within the cross-section, the strain (σm) felt by the material, formingeither high or low modulus zones, intersecting the cross-section willvary inversely with the modulus value of the material (e_(m)) as perequation (7). ##EQU1##

The above discussion represents a simplified version of materialbehavior with varying low and high modulus regions. However, itrepresents a good approximation of overall or regionalized filmbehavior. It will also work with preferential stress regions.

For a simplified basic embodiment where it is desired only to activatepredetermined areas, such as for the diaper tab of FIG. 17, transverseto the stretch direction, the discussion can be simplified. It isassumed that the non-preferentially activated areas are predominately,if not entirely, high-modulus material or non-preferential stressmaterial (as per FIG. 1). In the area to be preferentially activated, anextent transverse to stretch will preferably intersect lower modulus, orpreferential stress, material regions over at least 20% and morepreferably over at least 50% of its length. This will cause the laminateto preferentially activate in at least one area or zone. Generally, inthe non-preferentially activated areas or zone, the extents willintersect low modulus or preferential stress material regions by atleast 20% less, on average, than the corresponding extents in thepreferentially activated areas or zone(s), and more preferably will beat least 50% less. To ensure preferential activation, the extents in thenon-preferentially activated zones will most preferably be free of lowmodulus or preferential stress material regions over their length.Likewise, preferably, a lower modulus material region will extendcontinuously across the full extent of the preferentially activatedareas or zones of the film. Although not preferred for bothmanufacturing and practical reasons, multiple low modulus materialregions could define a single preferentially activated zone as definedabove.

Because of the desire to preferentially elasticize specific materialregions, areas or zones of a film, multiaxial stretching is not asdesirable as it is where the entire laminate is elasticized. Multiaxialstretching has the tendency to activate the entire laminate, at leastwhere one continuous elastomeric layer is used. However, multiaxialstretching is possible as long as at least the primary stretch directionis capable of preferentially activating areas or zones containing a lowmodulus or preferential stress material region(s) and the laminate isstretched to a degree sufficient to preferentially activate these zones.The remaining direction(s) of stretch, in most cases, will be orthogonalto the primary direction, which generally will be a direction notcapable of preferentially activating the low modulus or preferentialstress region containing zones. The degree of stretch in these secondarydirections must be less than that needed to activate the transverserelatively high modulus or non preferential stress regions, areas orzones if such activation is not desired.

Multiaxial stretching, however, may be desirable where a complexmicrostructure is desired. Biaxially stretching creates unique surfaceswhile creating a laminate which will stretch in a multitude ofdirections and retain its soft feel.

It has also been found that the fold period of the microstructuredsurface is dependent on the core/skin ratio. The periodicity is alsoindicative of the texture of the surface as per Table I. This is againanother indication of the control possible by careful choice of theparameters of the present invention.

When the laminate is stretched first in one direction and then in across direction, the folds formed on the first stretch become buckledfolds and can appear worm-like in character, with interspersed crossfolds as in FIG. 9. FIG. 9 is a laminate ofPP/styrene-isoprene-styrene(SIS)/PP with a core/skin ratio of 18(Example 23). Other textures are also possible to provide various foldedor wrinkled variations of the basic regular fold. When the film isstretched in both directions at the same time the texture appears asfolds with length directions that are random, as shown in FIG. 5 (alaminate prepared as per Example 19A with skin/core/skin thicknesses of5/115/5 microns respectively) or FIG. 10 (Example 23). Using any of theabove methods of stretching, the surface structure is also dependent, asstated before, upon the materials used, the thickness of the layers, theratio of the layer thicknesses and the stretch ratio. For example, theextruded multilayer film can be stretched uniaxially, sequentiallybiaxially, or simultaneously biaxially, with each method giving a uniquesurface texture and distinct elastomeric properties.

The unique continuous microstructured surfaces of the invention can bealtered and controlled by the proper choice of materials and processingparameters. Differences in the material properties of the layers canchange the resulting microtextured skin, but it has been found that bythe careful choice of the layer ratios, total laminate film thickness,the number of layers, stretch degree, and stretch direction(s) it ispossible to exercise significant control over the microstructure of thelaminate surface.

The degree of microtexturing of elastomeric laminates prepared inaccordance with the invention can also be described in terms of increasein skin surface area. Where the laminate shows heavy textures thesurface area will increase significantly. This is demonstrated forlinear low density polyethylene(LLDPE)/SIS/LLDPE laminates in TableVIII, Example 16. In this example, as the stretch ratio increases sodoes the percent increase in surface area, from the unstretched to thestretched and recovered laminate; from 280 at a stretch ratio of 5, to530 at a stretch ratio of 12. Generally the microtexturing will increasethe surface area by at least 50%, preferably by at least 100% and mostpreferably by at least 250%. The increase in surface area directlycontributes to the overall texture and feel of the laminate surface.

Increased opacity of the skin and hence the laminate also results fromthe microtexturing. Generally, the microtexturing will increase theopacity value of a clear film to at least 20%, preferably to at least30%. This increase in opacity is dependent on the texturing of thelaminate with coarse textures increasing the opacity less than finetextures. The opacity increase is also reversible to the extent thatwhen restretched, the film will clear again.

It is also possible to have more than one elastomeric core member withsuitable skins and/or tie layer(s) therebetween. Such multilayerembodiments can be used to alter the elastomeric and surfacecharacteristics of the laminate.

With certain constructions, the microtextured skin layers may tend todelaminate and/or the underlying elastomer may tend to degrade overtime. This tendency may particularly occur with ABA block copolymers.Residual stress created during the stretching and recovery steps ofactivating the material to its elastomeric form can accelerate thisprocess significantly. For those constructions prone to such degradationor delamination a brief relaxing or annealing following activation maybe desirable. The annealing would generally be above the glasstransition point temperature (T_(g)) of the elastomer, above the B blockT_(g) for ABA block copolymers, but below the skin polymer meltingpoint. A lower annealing temperature is generally sufficient. Theannealing will generally be for longer than 0.1 seconds, depending onthe annealing temperature. With commercial ABA block copolymers (e.g.,Kraton™ 1107) an annealing or relaxing temperature of about 75° C. isfound to be sufficient.

The skin layer-to-core layer contact in the stretched and activated filmhas been observed to vary depending on the skin and core compositions.With certain preferred constructions, the core and skin remain in fullcontact with the core material, filling the folds formed in the skinlayers as shown in FIG. 2. This construction is extremely durable andnot as subject to delamination, particularly when annealed followingactivation. A variation of this continuous contact construction is alsopossible where the elastomer fills the skin folds, but is observed tocohesively fail under the folds. It is believed this occurs with thickerand/or more rigid skins that expose the underlying elastic to moreconcentrated stresses during relaxation. An entirely different skin/coreadhesion method is also possible. Namely, the core, in some cases, cancompletely retract from the skin under the folds, but remainsufficiently attached such that the skin does not delaminate (seeExample 34, adhesive failure). This construction is not as desirable asduring use it is more easily subject to delamination as well as exposingthe elastic core to air which may accelerate degradation of theelastomer.

The laminate formed in accordance with the above description of theinvention will find numerous uses due to the highly desirable propertiesobtainable. For example, the microtexture gives the elastomeric laminatea soft and silky feel. The elastic activated portions of the laminatecan further be non-necking(i.e., will not tend to thin down whenrestretched). This renders the elastomeric laminate particularly wellsuited for a variety of commercially important uses particularly in thegarment area, where elastic webs are used in areas to engage or encirclea body portion alone or as part of a garment. Examples of such garmentsinclude disposable diapers, adult incontinence garments, shower caps,surgical gowns, hats and booties, disposable pajamas, athletic wraps,clean room garments, head bands for caps or visors or the like, anklebands (e.g., pant cuff protectors), wrist bands, rubber pants, wet suitsand the like.

The laminate can be extensively used in disposable diapers, for exampleas a waistband, located in either the front or side portions of thediaper at waist level, as leg elastic, as an outer cover sheet or inadjustable slip-on diapers, where the elastomeric laminate could be usedas, or in, side panels around the hip that have zones of elasticity tocreate a tight fitting garment. The laminates can be applied ascontinuous or intermittent lengths by conventional methods. Whenapplied, a particular advantage of the laminate is the ability to usethin elastomers with high stretch ratios while activation of theelastomeric laminate can occur at a controlled stretch ratio, dependingon the size of the low modulus regions, their activation stretch ratioand modulus behavior.

Garments often are shirred to give a snug fit. This shirring can beeasily obtained by applying the laminate while in an unstable stretchedcondition and then affecting the shirr by application of heat.

The elastomeric laminate can be adhered to the garment by ultrasonicwelding, heat sealing and adhesives by conventional methods. With theinvention laminate, adherence would be preferably in the non-activatedhigher modulus or non-preferential stress regions.

The application of adhesive can also be used to preferentially annealcertain portions of a cast laminate. Hot melt applied adhesives willcreate soft spots which will harden when cooled. The laminate can thenbe preferentially activated, e.g., with the low modulus regions beingthe continuous phase to provide adhesive coated unactivated areas. Thiswill allow the elastic to be attached to a substrate without subjectingthe adhesive to excessive shear forces caused by substrate movement.

Adhesive can also be applied to a skin layer face prior to activation.The microtexture formed on this skin in the activated areas or regionscan reduce the tack of the adhesive in the activated areas if theadhesive layer is approximately the size of the microtexture formed,generally less than 30 microns. This is advantageous Where the activatedelasticized area is preferable not permanently adhered to a substratesuch as in the diaper fastening tab depicted in FIG. 17.

The ability to create laminates with multiple texture types gives theinvention laminate great versatility. The film can be given a clothlikeor bulk feel by using patterns of preferentially and non-preferentiallyactivated regions allowing for general film activation with regions ofdiffering activations (i.e., stretch degree, skin thickness, skin type,etc.). This allows for the construction of an essentially infinitevariety of surface textures. Usable in a variety of situations, where aclothlike or like textured surface is desired with the properties of apolymeric and/or elastic film.

The controlled relaxation obtainable by adjusting the layer ratios,stretch ratio and direction, and layer composition makes the elastomericlaminate of the invention well suited to high speed production processeswhere heat activated recovery can be controlled easily by hot fluidssuch as hot air, microwaves, UV radiation, gamma rays, frictiongenerated heat and infrared radiation. With microwaves, additives, suchas iron whiskers, nickle powder or aluminum flakes, may be needed toensure softening of the skin to effect skin controlled recovery.

The counter-balancing of the elastic modulus of the elastomeric layerand the deformation resistance of the skin layer also modifies thestress-strain characteristics of the activated areas regions of thelaminate. The modulus of the elastic can therefore be modified toprovide greater wearer comfort when the laminate is used in a garment.For example, a relatively constant stress-strain curve can be achieved.This relatively constant stress-strain curve can also be designed toexhibit a sharp increase in modulus at a predetermined stretch percent,i.e., the point at which the skin was permanently deformed whenactivated as shown in FIG. 4, line Y. Prior to activation, the laminateis relatively rigid, line Z of FIG. 4, i.e., having a high modulusimparted due to the skin layer. The non-activated or non-stretchedlaminate is easier to handle and much better suited to high speedproduction processes than would be a conventional elastic. To achievethese benefits, the skin can be either an inner layer, an outer layer orboth. In FIG. 4, line ZZ is the skin alone and line X is the elastomericlayer alone.

Another use for the invention laminate would be as an elasticized diaperfastening tab as per, e.g., U.S. Pat. No. 3,800,796, shown in FIG. 17.The preferential activation area zone 6 can be placed at the desiredlocation while providing inelastic end portions 7. This tab could be cutfrom stock containing one or more preferential activation areas, zonesor regions. Adhesive 8 could then be applied to one or more faces of theinelastic end portions 7 or over the entire laminate as discussed above.

An additional advantage with forming fastening tabs of the inventionelastic is the versatility available. The tabs could be sold unstretchedand easily activated by the customer, alternatively the tab could beused stretched and activated, in both cases the tacky rubber will not beexposed. An additional advantage with a stretched and activated tab isthat the activated regions will have a surface microstructure which willtend to release adhesive tape at lower application pressures. Thisfeature can be used to form tabs with a desirable centrally locatedmechanical low adhesion backsize region, which is desirable forfastening tabs such as those disclosed in U.S. Pat. No. 4,177,812 (Brownet al.).

The following Examples are provided to illustrate presently contemplatedpreferred embodiments and the best mode for practicing the invention,but are not intended to be limiting thereof. Examples 1 and 4-29 areexamples of laminates suitable for post-formation treatment inaccordance with the teachings of the invention.

EXAMPLE 1

A continuous coextrusion was carried out to prepare three-layerlaminates with two outer layers of polypropylene and a core elastomericlayer of a styrene-isoprene-styrene block copolymer. A 2 inch (5.1 cm)screw diameter Berlyn™ extruder (Berlyn Corporation, Worchester, Mass.)was used to feed the elastomer layer (Kraton™ 1107, Shell ChemicalCompany, Beaupre, Ohio) and a Brabender™ 1.25 inch (3.18 cm) screwdiameter extruder (available from C. W. Brabender Instruments, Inc.,N.J.) was used to feed the two polypropylene (Escorene™ 3085, availablefrom Exxon Chem. Corporation, Houston, Tex.) layers into the Cloeren™feedblock, and were extruded through a single manifold 18 inch (46 cm)wide film die. The film was cast onto a 60° F. (16° C.) cast roll at14.7 ft/min (509 cm/min) at varying total caliper as described in TableI. Films of varying outer layer thickness were prepared.

The films were tested for relaxation by initially uniaxially stretching,each sample by hand to just short of its breaking point, which wasgenerally about 650%, releasing the sample, and observing any recovery.Recovery after initial draw was then categorized as instantaneousrecovery (I), slow recovery with time (T), heat required for recovery(H) and permanent deformation (P), i.e. no significant recovery. Resultsare shown in the following table.

                                      TABLE I                                     __________________________________________________________________________          TOTAL           CORE                                                          SKIN    CORE    THICKNESS      TEXTURE                                                                              % Change in                       SAMPLE                                                                              THICKNESS                                                                             THICKNESS                                                                             SKIN           OF     Width upon Re-                    NO.   (microns)                                                                             (microns)                                                                             THICKNESS                                                                             RECOVERY                                                                             LAMINATE                                                                             stretching sample                                                                      C.O.F.                                                                            Periodicity          __________________________________________________________________________    A     5       90      18      I      F      1.4          --                   B     8       145     18      I      F      2.8      0.59                                                                              10μ               C     12      175     14.6    I      M      2.0      0.67                                                                              45μ               D     7       54      7.7     I      F      2.0                               E     14      100     7.1     T      C      0        0.75                                                                              90μ               F     8       48      6       T-H    F      0                                 G     20      45      2.25    P      Smooth Did not recover                   __________________________________________________________________________

The texture of the laminate is evaluated both visually and by touchafter recovery and classified as fine (F), medium (M), coarse (C) orsmooth (no texture discerned). The texture was also measured objectivelyin samples B, C and E by the periodicity (distance between folds) of thesamples. It was noted that as the regular folds get coarser, they alsoappear larger and more widely spaced. Although the large folds are moresubject to having more random peak to peak distances, they are stillquite regularly spaced.

The samples were also tested for necking characteristics expressed as %change in width upon restretching of the sample. Although necking wasnot significant for any of these samples, generally as skin thicknessfell and the core to skin thickness ratio rose, necking increased.

Periodicity and C.O.F. are also shown for samples B, C and D which areboth inversely related to the core/skin thickness ratio. The originalC.O.F. for the samples was over 3.8, thus the microtexturing produced asignificant overall reduction of C.O.F.

EXAMPLE 2

Strip coextruded samples were prepared using a modular three zone die.The two outer zones were fed with a 1.75 in (4.445 cm) Prodex ™ (ProdexCorp., Fords, N.J., now H. P. M. Corp., Mt. Gilead, Ohio) extruder,while the center zone was fed with a 1.25 in (3.175 cm) Killion ™(Killion Extruders Inc., Cedar Grove, N.J.) extruder. The two skin andcore compositions and extruder speeds are listed below.

    ______________________________________                                        Center Zone Extruder                                                                             Outer Zone Extruder                                        ______________________________________                                        Sample #1 Fina 3576/98% Elvax 260/Fina 3576                                   2% CBE 41055E                                                                 Zone 1: 149° C.                                                                           Zone 1: 210° C.                                     Zone 2: 177° C.                                                                           Zone 2: 221° C.                                     Zone 3: 193° C.                                                                           Zone 3: 232° C.                                     Screw Speed: 12 rpm                                                                              Zone 4: 232° C.                                                        Screw Speed: 25 rpm                                        Sample #2 Fina 3576/49% Fina 3576/Fina 3576                                   28% Himont 6723                                                               21% Mineral Oil                                                               2% CBE 41055E                                                                 Zone 1: 80° C.                                                                            Zone 1: 210° C.                                     Zone 2: 135° C.                                                                           Zone 2: 221° C.                                     Zone 3: 205° C.                                                                           Zone 3: 232° C.                                                        Zone 4: 232° C.                                     Sample #3 Fina 3576/98% Kraton G-1657/Fina 3576                               2% CBE 24811S                                                                 Zone 1: 149° C.                                                                           Zone 1: 210° C.                                     Zone 2: 190° C.                                                                           Zone 2: 221° C.                                     Zone 3: 205° C.                                                                           Zone 3: 232° C.                                     Screw Speed: 5 rpm Zone 4: 232° C.                                                        Screw Speed: 40 rpm                                        Sample #4 Elvax 260/98% Elvax 240/Elvax 260                                   2% CBE 41055E                                                                  Zone 1: 132° C.                                                                          Zone 1: 138° C.                                     Zone 2: 160° C.                                                                           Zone 2: 165° C.                                     Zone 3: 193° C.                                                                           Zone 3: 188° C.                                     Screw Speed: 5 rpm Zone 4: 199° C.                                                        Screw Speed: 50 rpm                                        Sample #5 Elvax 450/98% Elvax 260/Elvax 450                                   2% CBE 41055E                                                                 Zone 1: 132° C.                                                                           Zone 1: 115° C.                                     Zone 2: 160° C.                                                                           Zone 2: 165° C.                                     Zone 3: 193° C.                                                                           Zone 3: 188° C.                                     Screw Speed: 5 rpm Zone 4: 199° C.                                                        Screw Speed: 71 rpm                                        Sample #6 Elvax 750/98% Kraton G-1657/Elvax 750                               2% CBE 24811S                                                                 Zone 1: 149° C.                                                                           Zone 1: 115° C.                                     Zone 2: 190° C.                                                                           Zone 2: 165° C.                                     Zone 3: 205° C.                                                                           Zone 3: 188° C.                                                        Zone 4: 199° C.                                     ______________________________________                                    

Fina ™ 3576 is a 9 melt index (m.i.) polypropylene homopolymer,available from Fina Oil and Chem. Co., Deer Park, Tex. Himont™ 6723(available from Himont U.S.A., Inc., Wilmington, Del.) is a 0.8 m.i.polypropylene homopolymer. Elvax™ 240, 260, 450 and 750, 28% vinylacetate(VA) (43 m.i.), 28% VA(6 m.i.), 18% VA(8 m.i.) and 9% VA(7 m.i.),respectively, are ethyl vinyl acetates available from Dupont Corp.,Wilmington, Del. CBE™ 41055E and 24811S are yellow and blue dyes inpolyethylene (55%) and polystyrene(52%) carriers, respectively,available from C. B. Edwards and Co. Inc., Minneapolis, Minn. Themineral oil is Amoco™ White Oil RM 0009-8 available from Amoco Oil Co.,Chicago, Ill.

EXAMPLE 3

The strip coextruded layers from Example 2 were formed into three layerlaminates.

The constructions for the three layered laminates are set forth in TableII below where the sample numbers for the layers refer to the samples ofExample 2.

                  TABLE II                                                        ______________________________________                                        Laminate  Skin       Core         Skin                                        No.       Layer      Layer        Layer                                       ______________________________________                                        i         S-1        Kraton ™ 1657                                                                           S-1                                         ii        S-4        Kraton ™ 1657                                                                           S-4                                         iii       S-2        Kraton ™ 1657                                                                           S-2                                         iv        S-5        Kraton ™ 1657                                                                           S-5                                         v         Fina 3576  S-3          Fina 3576                                   vi        Fina 3576  S-6          Fina 3576                                   vii       Elvax 750  S-6          Elvax 750                                   ______________________________________                                    

The laminate constructions and performances are schematically shownbelow. All samples were 25 mm wide and stretched to their natural drawratio (NDR). The thicknesses of the individual layers in each zone werea mean value determined by optical microscopy at 250×. The overalllaminate thickness was measured by a caliper gauge at the indicatedlocations. The length of the various zones is shown at initial andstretched (natural draw ratio) values.

The structural representation of the laminates shown below(the boxes)include in the boxes the caliper of the layers in each zone as measuredby optical microscopy at 250×.

The values shown below the structural representation of the laminate areoverall calipers measured by a caliper gauge at the indicated location.

    ______________________________________                                        Laminate i                                                                              Zone 1       Zone 2   Zone 3                                        Initial   25 mm        20 mm    25 mm                                         @ NDR     25 mm        40 mm    25 mm                                         ______________________________________                                                  0.053 mm     0.208 mm 0.069 mm                                                0.084 mm     0.079 mm 0.084 mm                                                0.051 mm     0.216 mm 0.071 mm                                      (0.307)                                                                              (0.269) (0.254) (0.521)                                                                              (0.244)                                                                             (0.269)                                                                             (0.269)                             mm     mm      mm      mm     mm    mm    mm                                  ______________________________________                                        Laminate ii                                                                             Zone 1       Zone 2   Zone e                                        Initial   25 mm        22 mm    25 mm                                         @ NDR     45 mm        68 mm    50 mm                                         ______________________________________                                                  0.058 mm     0.119 mm 0.058 mm                                                0.058 mm     0.091 mm 0.076 mm                                                0.064 mm     0.119 mm 0.056 mm                                      (0.282)                                                                              (0.254) (0.285) (0.318)                                                                              (0.257)                                                                             (0.241)                                                                             (0.259)                             mm     mm      mm      mm     mm    mm    mm                                  ______________________________________                                        Laminate iv                                                                             Zone 1       Zone 2   Zone 3                                        Initial   25 mm        17 mm    25 mm                                         @ NDR     30 mm        45 mm    29 mm                                         ______________________________________                                                  0.112 mm     0.119 mm 0.081 mm                                                0.091 mm     0.066 mm 0.091 mm                                                0.114 mm     0.114 mm 0.114 mm                                      (0.335)                                                                              (0.333) (0.318) (0.292)                                                                              (0.295)                                                                             (0.307)                                                                             (0.305)                             mm     mm      mm      mm     mm    mm    mm                                  ______________________________________                                        Laminate v                                                                              Zone 1       Zone 2   Zone 3                                        Initial   25 mm        11 mm    25 mm                                         @ NDR     25 mm        30 mm    25 mm                                         ______________________________________                                                  0.028 mm     0.025 mm 0.020 mm                                                0.142 mm     0.117 mm 0.089 mm                                                0.038 mm     0.023 mm 0.028 mm                                      (0.155)                                                                              (0.152) (0.145) (0.180)                                                                              (0.145)                                                                             (0.216)                                                                             (0.191)                             mm     mm      mm      mm     mm    mm    mm                                  ______________________________________                                        Laminate vi                                                                             Zone 1       Zone 2   Zone 3                                        Initial   25 mm         9 mm    25 mm                                         @ NDR     32 mm        27 mm    31 mm                                         ______________________________________                                                  0.036 mm     0.028 mm 0.033 mm                                                0.114 mm     0.196 mm 0.114 mm                                                0.033 mm     0.023 mm 0.028 mm                                      (0.216)                                                                              (0.208) (0.155) (0.249)                                                                              (0.145)                                                                             (0.216)                                                                             (0.249)                             mm     mm      mm      mm     mm    mm    mm                                  ______________________________________                                        Laminate vii                                                                            Zone 1       Zone 2   Zone 3                                        Initial   25 mm         9 mm    25 mm                                         @ NDR     30 mm        25 mm    28 mm                                         ______________________________________                                                  0.023 mm     0.031 mm 0.025 mm                                                0.155 mm     0.203 mm 0.140 mm                                                0.025 mm     0.031 mm 0.025 mm                                      (0.216)                                                                              (0.198) (0.158) (0.259)                                                                              (0.185)                                                                             (0.244)                                                                             (0.249)                             mm     mm      mm      mm     mm    mm    mm                                  ______________________________________                                    

In sample iii, the skin layers separated in the transition regionbetween zones on both sides of the laminate. In most instances wherethere was stretch in zones 1 and 3, this occurred almost exclusively inan area of these zones directly adjacent to zone 2. This was believeddue to lower overall calipers noticed in these regions.

EXAMPLE 4

A multilayer laminate was prepared by laminating cast laminates ofpolypropylene/Kraton™ 1107/polypropylene. The total thickness of eachcast laminate was 2.8 mil (0.062 mm). The core/skin ratio was 12:1. Thelaminated laminate was formed of 6 cast laminates in a hot press at 200°C. at 140 kilograms per square centimeter pressure for five minutes. Theformed film was then cooled in a 21° C. water bath. The resultinglaminate was 6 mil (0.15 mm) thick and appeared like the cast film butthicker. After stretching approximately 300% and instantaneous recovery,the film displayed a coarse microtextured skin and microtextured innerskin layers.

EXAMPLE 5

A continuous coextrusion was carried out to prepare three-layerlaminates with two outer layers of a 70/30 by weight blend ofpoly(vinylidene fluoride) (Solef™ 1012, Solvay Co., France) andpoly(methyl methacrylate) (VO44, Rohm and Haas Corp., Bristol, Pa.) anda core layer of Kraton™ 1107. A two inch (5.1 cm) diameter Berlyn™ screwextruder, at 10 RPM screw speed, was used to feed the core layer polymerand a 2 inch (5.1 cm) diameter screw Rheotec™ extruder, at 25 RPM, wasused to feed the skin layer polymer blends into a Cloeren™ feedblock andthe melt laminate was extruded through a single manifold die, 18 inches(46 cm) wide (Extrusion Dies, Inc., Chippawa Falls, Wis.), at 420° to450° F. (215° to 232° C.) onto a 78° F. (26° C.) cast roll at 17.0 or15.3 revolutions per minute (RPM), respectively. The film laminatethicknesses obtained were 5.5 and 6.0 mil (0.14 and 0.15 mm) withcore/skin(single) ratios of 6:1 and 7.5:1, respectively.

Both laminates were stretched 400% and allowed to immediately recover.In each case, a laminate with a fine glossy microtextured surface wasobtained.

EXAMPLE 6

A continuous coextrusion was carried out to prepare two distinctthree-layer laminates with two outer layers of a 50/50 blend of twopolybutylenes resins, Shell™ 0200 and Shell™ 0400, and a coreelastomeric layer of Kraton™ 1107. A two inch (95.2 cm) diameter screwBerlyn™ extruder was used to feed the Kraton™ 1107 at a screw speed of10 RPM. A 1.25 inch (3.18 cm) diameter Brabender™ screw extruder wasused to feed the two polybutylene blend layers at screw speeds of 10 and12 RPM into a Cloeren™ feed block. The laminates were extruded through asingle manifold 18 inch (46 cm) wide film die at 430° F. (221° C.) ontoa 60° F. (16° C.) cast roll at either 8.8 or 7.6 ft/min (2.7 or 2.3m/min), maintaining a total caliper of 0.003 inches (0.076 mm) for bothsamples. This produced two films of varying outer skin thicknesses withthe same total laminate thickness. The core/skin ratios were 13:1 and5:1, respectively.

Also, the same equipment was run at a Brabender™ extruder speed of 35RPM and a cast roll speed of 8.6 ft/min (2.6 m/min), all otherconditions the same as above, to give a 0.005 inch (0.127 mm) thicklaminate (comparative) with thick overall skin layers, and a core/skinratio of 2.6:1.

The texture for each sample was noted after each laminate was stretchedby hand just short of its breaking point, about 4:1, and allowed torecover, the first two runs instantly and the third (comparative) withheat. The textures were classified as very fine, fine and none. Thisdata is shown in Table III below.

                  TABLE II                                                        ______________________________________                                        Brabender ™                                                                            Cast Roll  Total Film                                             Speed       Speed      Thickness                                              (RPM)       (cm/min)   (cm)      Texture                                      ______________________________________                                        10          268        0.0081    very fine                                    12          232        0.0081    fine                                         35          262        0.013     none                                         ______________________________________                                    

EXAMPLE 7

A continuous coextrusion was carried out to prepare five-layer laminateswith two outer layers of linear low density polyethylene, tie layers ofethylene vinyl acetate, Elvax™ 260(EVA) (available from DupontCorporation, Wilmington, Del.) and a core elastomer layer ofstyrene-isoprene-styrene block copolymer. A two inch (5.1 cm) screwdiameter, 4D ratio Berlyn™ extruder was used to feed the elastomer layer(Kraton™ 1107). A Rheotec™ two inch (3.18 cm) screw diameter extruderwas used to feed the two polyethylene layers, and a one inch (2.54 cm)screw diameter 3M made extruder was used to feed the two Elvax™ layersinto a Cloeren™ feedblock.

The laminates were extruded through a single manifold 18 inch (46 cm)wide film die at 375° F. (190° C.) onto a 60° F. (16° C.) cast roll atvarying total caliper or thickness as described in Table IV. Films ofvarying layer thickness were thus prepared. This example alsodemonstrates how casting roll speed affects film thickness.

The EVA tie layers add bonding strength between the LLDPE outer layersand the SIS core layer, resulting in a more durable laminate than such afilm without the EVA, yet do not interfere with the way the laminatebehaves with respect to surface texture. These tie layers are, ofcourse, very thin compared to the other layers.

                                      TABLE IV                                    __________________________________________________________________________    PROCESSING CONDITIONS FOR SAMPLES                                                                CASTING                                                                             NIPP FILM SUR-                                                          ROLL  ROLL THICK-                                                                             FACE*                                                                              1"                                       BERLYN+                                                                              RHEOTEC++                                                                              SPEED SPEED                                                                              NESS TEXT-                                                                              EXT.'                                 NO.                                                                              RPM    RPM      (RPM) (RPM)                                                                              (microns)                                                                          URE  RPM                                   __________________________________________________________________________    7A 30     8        15    15   132.0                                                                              F    24                                    7B 30     8        15    15   132.0                                                                              F    24                                    7C 30     8         7     7   272.0                                                                              MF   20                                    7D 30     8         4     4   508.0                                                                              C    20                                    7E 30     8        14    14   124.0                                                                              F    20                                    7F 30     8        25    25   71.0 VF   20                                    7G 30     8        48    48   25.4 SF   20                                    __________________________________________________________________________     + Berlyn ™ extruder temperature same for all samples: Zone 1 =             149° C., Z2 = 177, Z3 = 193, Z4 = 204, Z5 = 204, Z6 = 204              ++ Rheotec ™ extruder temperature same for all samples: Zone 1 =           110° C., Z2 = 149, Z3 = 149, Z4 = 160                                  ' 1"  (2.54 cm) extruder temperature same for all runs: Zone 1 = 143          ° C., Z2 = 191, Z3 = 191                                               *F = Fine microtexture, MF = medium fine, VF = very fine, SF = super fine     C = coarse                                                               

Since the extruder conditions were close to constant for all of theabove runs, the core thickness to skin thickness ratio will be the samefor all of the above runs, approximately 13:1 as will be the core/tielayer ratio at 30:1. Thus, it will be noted that the total filmthickness column of Table IV correlates exactly with the surface texturecolumn. The range of values goes from a total film thickness of 1.0 mil(25 microns) and a texture of super fine, to 20.0 mil (508 microns) anda texture of coarse, all from a stretch of 5:1 and an instantaneousrecovery. Thus, it can be seen that the thicker materials give coarsertextures and that by controlling the physical parameters, the texturecan be controlled.

EXAMPLE 8

A three-layer LLDPE/SIS/LLDPE film was made as in the previous examplesusing a Berlyn™ extruder with a screw speed of 20 RPM to feed theKraton™ 1107, and a Brabender™ extruder with a screw speed of 17 RPM tofeed the Dow Chemical Co. (Rolling Meadows, Ill.) 61800 linear lowdensity polyethylene to a Cloeren™ feedblock. The laminate was extrudedthrough a single manifold 18 inch (46 cm) wide film die onto a castingroll at 85° F. (29° C.), and a speed of 13.7 ft/min (4.18 m/min) to givea laminate with a core/skin ratio of 15.6:1 and a total thickness of 125microns. The film was uniaxially stretched 4:1 and instantaneouslyrecovered, the coefficient of friction of the film, to itself, wasmeasured from the stretched and recovered film, and compared to theunstretched film. The data is shown in Table V. MD denotes Machinedirection and TD denotes transverse direction.

                  TABLE V                                                         ______________________________________                                        Sample         Static COF                                                                              Dynamic COF                                          ______________________________________                                        unstretched MD 4.5       4.2                                                  unstretched TD 4.6       3.7                                                  stretched MD   0.4       0.3                                                  stretched TD   0.5       0.5                                                  ______________________________________                                    

This data is indicative of the large drop in the coefficient of frictionfor the stretched film compared to its unstretched precursor and is alsoindicative of the unique microtextured surface of laminates of thepresent invention.

EXAMPLE 9

A three-layer laminate of the present invention was made using theset-up of Example 8. The Berlyn™ extruder, operating at a screw speed of10 RPM, was used to feed a polyurethane (Pellethane™ 2102-75A from DowChemical Co., Midland, Mich.) core material. The Brabender™ extruderoperating at a screw speed of 7 RPM was used to feed a blend of Amoco™(Amoco Oil Co., Chicago, Ill.) 3150B high density polyethylene (HDPE)and Kraton™ 1107 in a 95:5 ratio, as the skin material, to the Cloeren™feedblock. The small amount of Kraton™ 1107 was added to the skin layerto increase the adhesion of the skin layer to the core layer. Thelaminate was extruded through a single manifold, 18 inch (46 cm) wide,film die onto a casting roll at a temperature of 70° F. (21° C.) and aspeed of 21 ft/min (6.4 m/min) to give a 69 micron laminate with acore/skin ratio of 13.7:1. The laminate exhibited a microtexturedsurface after stretching 600% and instantaneous recovery.

EXAMPLE 10

A three-layer laminate of the present invention was made using the setup of Example 8. The Berlyn™ extruder operating at a screw speed of 60RPM was used to feed a triblock copolymer elastomer ofstyrene-butadiene-styrene (SBS) (Kraton™ 1101) as a core material, and aKillion™ extruder was used to feed a Dow™ 3010 LLDPE material to aCloeren™ three layer die. The extrudate was cast upon a casting roll ata temperature of 85° F. (29° C.) and a speed of 41 ft/min (12.5meters/minute). The resulting 5 mil (0.127 mm) thick film with acore/skin ratio of 8.9:1 was easily stretched 7.5:1 and uponinstantaneous recovery a fine textured laminate was formed.

EXAMPLE 11

A three-layer laminate, of the present invention, made using the set upof Example 4, with the Berlyn™ extruder feeding a Kraton™ G 2703styrene-ethylene butylene-styrene (SEBS) block copolymer at a screwspeed of 20 RPM, and the Brabender™ extruder feeding an Exxon™ PP-3014polypropylene at a screw speed of 5 RPM, to a Cloeren™ feedblock. Thismaterial was then extruded through a 18 inch (46 cm) film die onto acasting roll at a temperature of 34° F. (1.1° C.). The film produced waseasily stretched 600% and formed a fine textured surface after it wasallowed to recover instantaneously. The layer thicknesses determinedunder a light microscope were 15/162/12 microns skin/core/skin,respectively.

EXAMPLE 12

This example demonstrates the use of varying skin and core materials. Inall runs, the line conditions were identical using a Cloeren™ feedblockat 400° F. (204° C.). The core extruder was the Brabender™ discussedabove with temperatures in zones 1-4 of 178°, 210°, 210° and 216° C.respectively. The die was at 400° F. (204° C.) and the casting wheel at51° F. (11° C.).

                                      TABLE VI                                    __________________________________________________________________________                      CORE SKIN                                                                            %     SHRINK-                                        #  CORE  SKIN     RATIO  STRETCH                                                                             AGE   TEXTURE                                  __________________________________________________________________________    12A                                                                              Kraton ™                                                                         ELVAX ™ 360                                                                         9.6    700   I     F                                           1107                                                                       12B                                                                              Kraton ™                                                                         (Polyester)                                                                            4.4    600   I     F                                           1107  (Eastabond ™                                                               FA-300)                                                              __________________________________________________________________________

12A in Table VI demonstrates that elastomers can be used for the skinwhen a more elastic core is used and with appropriate stretch for a 115micron film. 12B demonstrates the use of a polyester skin in a 120micron film. The laminate designated 12B, despite the relatively largecore to skin ratio, the skin was of a relatively fine texture andinstant shrink recovery. This is due primarily to the low modulus of thepolyester. FA-300 is available from Eastman Chem. Co., Kingsport, Tenn.

EXAMPLE 13

Nylon 66 (Vydyne™ 21 of the Monsanto Co., St. Louis, Mo.), thecondensation product of adipic acid and hexamethylene diamine, was usedas the skin in accordance with the procedure outlined in Example 8. Thecore was a SIS (Kraton™]1107) block copolymer. The nylon and Kraton™were extruded at 525° F. (274° C.) and 450° F. (232° C.), respectivelyinto a 500° F. (260° C.) die. A 4 mil (0.1 mm) thick film was formedwith a core to skin ratio of 18:1. A microtextured surface formed aftera 4:1 stretch and instant recovery.

EXAMPLE 14

In order to increase the tackiness of the core and lower core layermodulus and decrease its viscosity, a solid tackifying rosin Wingtack™(Goodyear Chem Co., Akron, Ohio) was blended with Kraton™ 1107 in ratiosof 10/90, 20/80 and 30/70 using the arrangement of the previous example,in 91, 114 and 165 micron films, respectively. The die temperature was380° F. (193° C.) with the Kraton™ blend fed at a rate of 18.5pounds/hour (0.14 kg/min) and the polyethylene skin (LLDPE; Dowlex™2500, Dow Chemical) fed at a rate of 6 pounds/hour (2.72 kg/hr). Thecore to skin ratios were 6.2:1. For all three Kraton™ blends a finemicrotextured surface of the laminate was obtained when a 6:1 stretchwas employed and gave instant shrink recovery.

EXAMPLE 15

The relationship between skin thickness and percent stretch to surfacetexture (measured by periodicity) was explored using a SEBS core(Kraton™ G1657) and a polypropylene skin (Exxon™ 3085). The Berlyn™extruder was used for the core and the Rheotec™ extruder was used forthe skin, fed into a Cloeren™ feedblock. A single layer drop die wasused at 420° F. (216° C.), the casting roll operated at 38.9 ft/min(11.9 m/min.) and 50° F. (10° C.). The results are shown in Table VIIbelow.

                  TABLE VII                                                       ______________________________________                                             AVG.                                                                          SKIN      CORE/            PERIOD- SHRINK                                     THICK-    SKIN     STRETCH ICITY   MECH-                                 #    NESS (μ)                                                                             RATIO    %       (μ)  ANISM                                 ______________________________________                                        15A  14        6        600     29      I                                                             250     56      I                                     15B  17.5      6.1      550     39      I                                                             350                                                   15C  21        4.4      550     46      H                                                             350     71      H                                     15D  20        4.3      550     47      H                                                             300                                                   15E  23        3.7      500     63      H                                                             350     69      H                                     ______________________________________                                    

As the stretch percent increased for each sample, the periodicitydecreased indicative of the finer microtexturing obtained. This showsthat stretch percent can be used to vary the surface structure of thelaminate.

Further, as skin thickness increased so did the periodicity. In allsamples, the core thickness was approximately constant at 85 μ's. Skinthickness on a constant core can thus be directly related to the surfacetexture obtainable. As can be seen in the above Table IV, for relativelyconstant stretch % as the skin thickness increased so did theperiodicity. The thick skinned samples thus produced coarser textures.This can of course be used to manipulate the skin and hence laminatecharacteristics.

EXAMPLE 16

The sample tested was that prepared in Example 8 the stretch ratio wasvaried from 2:1 to 13:1.

                  TABLE VIII                                                      ______________________________________                                        Stretch ratio                                                                             Periodicity (μ)                                                                          % Area Increase                                     ______________________________________                                        2           (random wrinkles)                                                 3           30                                                                4           12                                                                5           10            280                                                 6           8                                                                 7           7                                                                 8           6.5           390                                                 9           6                                                                 10          5.5                                                               11          5                                                                 12          4             530                                                 13          3                                                                 ______________________________________                                    

As can be seen from Table VIII, the relationship between stretch ratioand periodicity demonstrated in Example 15 holds up for thisLLDPE/SIS/LLDPE laminate. As the stretch ratio increases, theperiodicity decreases first rapidly, then slowly in a substantiallyexponential manner. Further, the increase in area increases with anincrease in stretch ratio.

EXAMPLE 17

The relationship between stretch, core/skin ratio and shrink mechanismwas demonstrated using the procedure of Example 4 and Example 15 forpolypropylene/Kraton™ 1657 (SEBS)/polypropylene laminates. The materialwas stretched at the rate of 5 cm/sec. and held for 15 seconds. The filmwas allowed to shrink for 20 seconds and then heat shrunk in a waterbath for 5 seconds at 160° F. (71.1° C.).

The length of the film after shrink was then compared to the length ofthe film after the 20 second hold period and the length after stretch todetermine the shrink mechanism in operation. The results of thiscomparison are in Table IX below.

                  TABLE IX                                                        ______________________________________                                        CORE/SKIN     STRETCH   SHRINK                                                RATIO         RATIO(S)  MECHANISM                                             ______________________________________                                        6.0           3.8/5.3/6.2                                                                             I                                                     5.3           4.6/5.3   S                                                                   6.5       I                                                     5.1           4.3/5.0   H                                                                   5.5       S                                                                   6.8       I                                                     4.8           4.2/4.0   H                                                                   6.0       T                                                                   6.5       F                                                     4.0           4.0/5.2/6.0                                                                             H                                                     3.7           4.2-6.8   H                                                     3.4           4.0       N                                                                   4.7-6.0   H                                                     ______________________________________                                         N = None,                                                                     H = Heat,                                                                     S = Slow time,                                                                T = Time,                                                                     F = Fast time,                                                                I = Instant                                                              

Fast is when more than 15% recovery occurred at 5 seconds. Medium timeis where greater than 15% recovery occurred at 20 seconds. Slow time iswhere greater than 15% recovery was not noted until 60 seconds afterstretch.

EXAMPLE 18

Polypropylene (Exxon™ 3145) was added to a Kraton™ 1107 (SIS) elastomeras a modifier for the core material. The skin used was an Exxon™ 3014polypropylene (PP). The cores prepared contained 5 to 10 percent Exxon™3145 polypropylene by weight. The relationship between stretch, theshrink mechanism and texture was tested. The results are i the followingTable.

                  TABLE X                                                         ______________________________________                                        Core/Skin Ratio = 6.9, 112 microns thick, 10% PP in Core                      % Stretch    320     410     510   590                                        Shrink Mechanism                                                                           None    None    Heat  Heat                                       Texture      --      --      Coarse                                                                              Coarse                                     Core/Skin Ratio = 8.0, 125 microns thick, 10% PP in Core                      % Stretch    280     380     480   570                                        Shrink Mechanism                                                                           None    None    Heat  Heat                                       Texture      --      --      Coarse                                                                              Coarse                                     Core/Skin Ratio = 8.8, 84 microns thick, 5% PP in Core                        % Stretch    270     320     400   500   590                                  Shrink Mechanism                                                                           Heat    Heat    Heat  Slow  Fast                                                                    Time  Time                                 Texture      Coarse  Coarse  Coarse                                                                              Med   Fine                                 ______________________________________                                    

As can be seen the addition of PP to the core decreases theshrinkability of the laminate. The polypropylene appears to reduce theelasticity of the core thereby permitting the restraining forces of theskin to more easily dominate the elastic strain imposed by the deformedelastic core.

EXAMPLE 19

The effect of adding a stiffening aid, polystyrene, to an elastomericcore material was tested. The skin comprised a linear low densitypolyethylene (Dowlex™ 6806). The core was a blend of SIS (Kraton™ 1107)and polystyrene (500PI or 685W, both from Dow Chemical Co.). All sampleswere of a 3-layer construction (skin/core/skin) with a total thicknessof 4.5 mil (0.11 mm) and a core/skin ratio of 8:1. All samples were thenstretched 400% and instantaneously recovered. Tensile curves were thengenerated which demonstrated that the laminates became stiffer withincreasing polystyrene content (as shown in FIG. 8 (T-N), shown also inthe following Table XI.

                  TABLE XI                                                        ______________________________________                                                             5% YOUNGS MODULUS                                        SAMPLE #  % P.S.(Type)                                                                             (kg/cm.sub.2)                                            ______________________________________                                        19A(T)     0         11.5                                                     19B(S)    10 (500 PI)                                                                              20.7                                                     19C(R)    30 (500 PI)                                                                              29.4                                                     19D(P)    40 (685 W) 68.6                                                     19E(N)    50 (685 W) 188.4                                                    ______________________________________                                    

EXAMPLE 20

In this example, the effect of the addition of Wingtack™ tackifier tothe core elastomer was investigated. The laminate material of Example 14was compared to a three-layer laminate (20) comprising LLDPE/Kraton™1107/LLDPE. Both samples were 4 mil (0.10 mm) in total thickness withcore/skin ratios of approximately 8:1. These materials were of theinstant shrink type when stretched from 4:1 to 13:1.

                  TABLE XII                                                       ______________________________________                                        EXAMPLE         5% YOUNGS MODULUS                                             ______________________________________                                        20 (Comp)       109 kg/sq.cm.                                                 14               47.9 kg/sq.cm.                                               ______________________________________                                    

As can be seen from Table XII, the use of a viscosity reducingaid/tackifier has the opposite effect as the addition of a polystyrenestiffening aid.

EXAMPLE 21

A 2 layer laminate of a core and one skin layer was formed of Kraton™1107 (SIS)/Exxon™ polypropylene 3014. A Berlyn™ extruder operating at 6RPM was used with the polypropylene and the Killion™ extruder operatingat 125 RPM was used for the Kraton™. The polymers were fed to an 18 inch(45.7 cm) 440° F. (227° C.) Cloeren™ die with one manifold shut down.The resulting film was cast on a roll at 60° C. and rotating at 35.2RPM. The laminate formed was 2 mil (0.051 mm) thick with a core/skinratio of 2.5:1 and exhibited a coarse microtexture when stretched 5:1and allowed to recover instantly. Necking on subsequent restretching wasonly 2.5%.

EXAMPLE 22

A laminate was formed having skins of different compositions. Theelastic core was Kraton™ 1107 with one polyethylene (Dow™ LLDPE 61800)and one polypropylene (Exxon™ 3085) skin. The core was extruded with aBerlyn™ extruder while the skins were extruded with Rheotec™ andBrabender™ extruders, respectively. The Cloeren™ die was at 350° F.(177° C.) and the casting roll at 60° F. (16° C.). Two films wereformed. For the first, the extruders operated at 20, 8 and 26 RMP'srespectively while the cast roll operated at 17.3 RPM to form laminateswith core/skin ratios of 18:1. The sample formed was instant shrink at a5:1 stretch, with a fine microtexture. For the second film, theextruders and cast roll operated at 10, 16, 26 and 14.2 RMP'srespectively to form a laminate with a core/skin ratio of 18:1. Thesecond laminate was also instant shrink at 5:1 stretch yet exhibitedcoarse surface texture. Both laminated were 4.0 mil (0.1 mm) thick.

EXAMPLE 23

The laminate of Example 1A was stretched in a first direction at 4:1 andsequentially in a cross direction by 4:1 and simultaneously biaxially at4:1 by 4:1. The laminates were of the instant shrink type. The textureformed is shown in FIGS. 9 and 10, respectively.

EXAMPLE 24

A three-layer laminate of polypropylene/SEBS(Kraton™ 1657)/polypropyleneused in Example 17 was tested for writability. The core/skin ratio was5:1 with a total laminate thickness of 5 mil (0.13 mm). The film wasstretched to 5:1 and allowed to recover. The writability before andafter stretching is shown in FIGS. 6 and 7, respectively.

EXAMPLE 25

A series of LLDPE/SIS/LLDPE laminates were compared for theirnon-necking characteristics, as shown in Table XIII below.

                  TABLE XIII                                                      ______________________________________                                                        STRETCH   THICKNESS % WIDTH                                   #    C/S RATIO  RATIO     (microns) CHANGE                                    ______________________________________                                        A    8.75       5:1       215       2.8                                       B    6.0        5:1       120       3.2                                       C    6.7        5:1        78       5.2                                       D    15.3       7:1       100       10.0                                      E    21.2       8:1       132       33.3                                      F    PURE SIS   5:1                 50.0                                      G    "          7:1                 62.5                                      H    "          8:1                 70.8                                      ______________________________________                                    

SIS was tested for comparison purposes. As the C/S ratio and stretchratios rose, the problems with necking increased.

EXAMPLE 26

The use of adhesive cores was demonstrated. First a copolymer ofisooctyl acrylate (IOA) and acrylic acid (AA) in monomer ratios of(90/10) was used as a core with polypropylene (Exxon™ 3014) and PET(intrinsic viscosity 0.62) as the skins in the first two examples. TheIOA/AA copolymer was prepared in accordance with U.S. Pat. No.4,181,752. The core/skin ratios and total thicknesses were 20 and 10,and 22 mil (0.56 mm) and 6 mil (0.15 mm) before lamination for the PPand PET examples, respectively. The laminates were cured for 5 minutesusing a 15 watt UV light to cure the cores. The PP skin embodiment wasan instant shrink at 500% stretch while the PET skin embodiment was aheat shrink laminate at 400% stretch.

PET was also used as a skin layer for a Kraton™ 1107 (56 parts) WingtackPlus™ (35 parts) and Wingtack™ 10 (9 parts) core with a core/skin ratioof 83.1 and a total thickness of 25.6 mil (0.65 mm) before lamination.This laminate was of the instant shrink type at 400% stretch.

EXAMPLE 27

This example demonstrates skin controlled relaxation in the heat shrinkregion and control of the heat shrink mechanism by % elongation andcore/skin ratio. A series of 5 mil (0.12 mm) laminates were made with acore of Kraton™ 1107 (89 parts) poly(alpha-methyl)styrene (PAMS) (10parts) and Irganox™ (Ciba-Geigy Corp., Hawthorne, N.Y.) (1part-antioxidant). The skins were polypropylene (Exxon™ 3085). A Berlyn™extruder was used for the core and Rheotec™ extruders for the skin usinga Cloeren™ three-layer feedblock and a 18 inch (45.7 cm) film die. Thecast wheel temperature was 80° F. (27° C.) with the speed determined bythe core/skin (C/S) ratio and the skin extruder speed. The shrinkmechanism as a function of C/S ratio and % stretch is shown in FIG. 11.Fast is when more than 15% recovery occurred at 5 seconds. Medium timeis where greater than 15% recovery occurred at 20 seconds. Slow time iswhere greater than 15% recovery was not noted until 60 seconds afterstretch.

Skin control of the temperature of activation for the heat shrinkmaterial is demonstrated in FIG. 12. The temperature of activation isdefined as the temperature required to achieve 50% or 90% of therecovery obtainable. Lines V and W represent samples with core/skinratios of 4.71 and 4.11, respectively. As is seen, as the core/skinratio went down the temperature of activation (both T_(a-90) andT_(a-50)) went up, indicating a skin controlled relaxation. In thisFigure, the 100% value is defined as the % shrinkage at 160° F. (71°C.), which for most practical purposes was the upper limit of availablerecovery. The points below 80° F. (27° C.) are the amounts ofpreactivation shrinkage for each example.

Three samples were also tested for increase in opacity from theunstretched clear film as seen in Table XIV below.

                  TABLE XIV                                                       ______________________________________                                                                                OPA-                                  CORE*/                   SHRINK         CITY                                  SKIN   %         TEX-    MECH-  OPACITY ACTI-                                 RATIO  STRETCH   TURE    ANISM  AS CAST VATED                                 ______________________________________                                        4.71   300       C       H      2.42%   30.4%                                 4.97   700       F       I      2.08    37.5                                  5.0    300       C       H      3.40    35.8                                  ______________________________________                                         *The core had a 1/2% blue pigment.                                       

EXAMPLE 28

A foamed core three-layer film was made. The skins were Dow™ LLDPE 6806and the core was 99.5% Kraton™ 1107 with 0.5% AZNP 130 blowing agent(Uniroyal Chemical Co., Naugatuck, Conn.). Total film thickness was 20mil (0.5 mm). The skins were 2.0 mil (0.05 mm) thick each. The foamedcore specific gravity was 0.65 as compared to unfoamed Kraton™ specificgravity of 0.92. A three-layer coextrusion die was used. This was aninstant shrink sheet exhibiting a coarse texture at about 300% stretch.

EXAMPLE 29

The film with a core/skin ratio of 6:1 was characterized for itsunstretched and stretched modulus value, the results of which are shownin FIG. 4; X is the Kraton™ 1107 elastomer alone, ZZ is the polyethyleneskin alone, Z is the laminate as cast and Y is the laminate afterstretching to 500% and recovery.

EXAMPLE 30

A laminate sample, similar to Example 27, having a skin/core ratio of8.28 and of the instant shrink type, was annealed. The sample wasmounted onto a sheet of white paper having alternating zones of blackand white. The so-mounted sample was then placed in an overheadtransparency maker, 3M Model 4550 AGA (available from 3M Co., St. Paul,Minn.), at setting 2 (relating to the speed at which the sample goesthrough the machine) and exposed. The sample was exposed to a 1350 wattbulb which melted the skin layers at this setting(T>185° C.). Thetransparency maker heated the laminate surface adjacent to the darklines, thus annealing the sample. The sample was annealed to give 25%,50%, 75% and 100% overall annealing as per FIG. 13. One inch (2.54 cm)wide stripes were tensile tested according to ASTM D 882. The jaw gapwas 4 inches (10.15 cm) with a crosshead speed of 20 inches (50.8)cm)/min. The tensile curves are shown in FIGS. 14 (A)-(C). A summary ofthe data is set forth in Table XV below.

                  TABLE XV                                                        ______________________________________                                              Prim.                                Sec-                                     Yield   Prim.   Young's                                                                              Load @ Second.                                                                              ond.                               Sam-  (Kg/    Yield   Modul. 500% El.                                                                             Yield  Yield                              ple   cm.sup.2)                                                                             (% E)   (Kg/cm.sup.2)                                                                        (Kg)   (Kg/cm.sup.2)                                                                        (% E)                              ______________________________________                                        As    42.5    16.3    1.12   2.09   --     --                                 Cast                                                                          25%   46.2    11.0    1.43   2.05   49.6   174                                50%   48.0    9.9     1.39   2.14   51.3   115                                75%   50.5    9.0     1.58   2.00   53.1    93                                100%  56.3    13.5    1.59   2.04   --     --                                 ______________________________________                                    

The sample was annealed at a lower setting (4.5-faster) with a diamondpattern. A thermometer ran through the machine at this setting read 180°C. The sample was stretched and relaxed and formed a complex yetrepeating macrostructured surface as shown in FIG. 16 (The marks at thebottom of the figure represent millimeters.).

FIGS. 15 (A)-(C) are a series of scanning electron micrographs of the25% annealed sample as cast, stretched to its natural draw ratio andrelaxed. The samples were prepared at the 4.5 setting discussed above.This series of figures shows the preferential elongation in theunannealed zones. This preferential strain is also summarized in TableXVI below.

                  TABLE XVI                                                       ______________________________________                                                Total Stretch                                                                              Am. Stretch                                                                              Cryst. Stretch                                Samples (%)          (%)        (%)                                           ______________________________________                                        25% Crys.                                                                             100          120        25                                            50% Crys.                                                                             70           162        23                                            75% Crys.                                                                             77           200        22                                            ______________________________________                                    

The samples above were stretched to the point where the crystallinematerial was about to stretch. The percentages represent the amountsthat each region and the overall composite stretched at this point.

COMPARATIVE EXAMPLE 1

A three-layer film of Dow™ LLDPE 2517 (Polyethylene)/Pebax™ (availablefrom Autochem Co., France) 3533/Dow™ LLDPE 2417 was made. The film wasformed by pressing three precursor films together at 400° F. (204° C.)and about 2000 pounds of pressure (140 kg/sq.cm) for 5 minutes. The filmformed was 5 mil (0.13 mm) thick with a core/skin ratio of 12.7. Thelaminate was stretched 400% (from 1 to 5 cm). The stretched laminatethen contracted to 3.2 cm (36% of stretched length) at room temperature.The relaxed laminate was then heat shrunk by 180° F. (82° C.) air, andit contracted to 1.5 cm (53% of relaxed length). An edge of the samplewas then cut and observed for microtexturing. No folds were observed at1000× magnification. Microscopic bumps, probably formed by recompressionof the cover layer, and skin delamination was observed. The COF andopacity for the cast laminate was 0.901 and 2.77% while that for therelaxed activated laminate was 0.831 and 12.4%, respectively.

EXAMPLE 31

The material from Example 15 was scored a multitude of times using adull edged roller, by hand. This produced indentations in the laminate.When the laminate was elongated 100% and instantaneously recovered,elastic activation occurred in the regions around the score lines. Thisis significant in that ordinarily this material must be elongated by300% or more to get a uniform draw and activation.

EXAMPLE 32

A film laminate of PP(EXXON 3085)/SIS(Kraton™ 1107)/PP was treated bycorona discharge. The SIS core contained 1% pigment, 1% Irganox 1076(Ciba Geigy Inc., Hawthorne, N.Y.) and 10% (based on the elastomer andthe PAMS) Exxon PAMS 18-210. The overall caliper of the laminate was 3.6mils (0.0914 mm) with a core/skin ration of 5.1:1. The laminate wascorona treated at 100° F. (37.8° C.) and 53% relative humidity. A coronaoperating at 1.86 KW, per side, was used to treat the laminate runningat less than 10 feet (3.05 m) per minute. The line speed was slowed downby hand(approximately 7 feet/min (2.13 m/min)) to create regions ofheavy corona treatment and light corona treatment. The areas of heavycorona treatment preferentially activated.

EXAMPLE 33

The film laminate of Example 32 was treated on the same line withoutslowing the line down to cause ablation. The temperature was the sameand the relative humidity was 50%. The laminate was taken off normal tothe line and at a sharp angle (approximately 110°) to create microcracks. When stretched the laminate activated preferentially in theareas where microcracks were formed.

EXAMPLE 34

The film laminates of certain examples were examined to determined thecontact mechanism between the skin and core layers. The stretched andactivated samples were cut with a razor blade on a hard surface. Thesamples were then examined at the cut edges with a scanning electronmicroscope. The core skin contact was then determined visually with theresults summarized in Table XVII below.

                  TABLE XVII                                                      ______________________________________                                        Pat                      Stretch                                              Ex   Composition         Ratio   Comments                                     ______________________________________                                         5   PVDF + PMMA/SIS/PVDF +                                                                            2.2     Elastic cohesive                                  PMMA                        failure                                       6   PB/SIS/PB           3       Elastic cohesive                                                              failure                                       7   PE/EVA/SIS/EVA/PE   5       Adhesive                                                                      failure                                      12A  EVA/SlS/EVA         4       Adhesive                                                                      failure                                      12B  FA300SIS/FA300      7       Adhesive                                                                      failure                                      19E  PE/SIS + PS/PE      3       Some voids                                    8   LLDPE/SIS/LLDPE     3       Filled                                                                5       Filled                                                                7       Filled                                       15A  PP/SEBS/PP          4       Filled                                       15C  PP/SEBS/PP          5.3     Elastic cohesive                                                              failure                                       A   PP/SIS/PP                   Filled                                       ______________________________________                                    

New sample A corresponds in Example 27. Sample A had approximately thecaliper of the Example 27 sample with a core/skin ratio of 5.1 and was aheat shrink laminate.

EXAMPLE 35

A sample having the layer composition of Example 27 (with 1% bluepigment in the core) was formed with an overall caliper of 2.98 mils(0.076 mm) and a core/skin ratio of 5.14. The film was cast onto achrome casting wheel with a rubber nip. The 60° gloss was measured usingASTM D2457-70 using a Gardner Instruments(Bethesda, Md.) 60° glosstester. The results are summarized in Table XVIII below for the as castand three microtextured films (with different stretch rates).

                  TABLE XVIII                                                     ______________________________________                                                            60° Gloss                                                              MD   TD                                                   ______________________________________                                        As Cast     Chrome Side   8.6    8.8                                                      Rubber Side   3.4    3.3                                          300%        Chrome Side   2.1    3.5                                                      Rubber Side   1.5    1.9                                          400%        Chrome Side   2.0    6.6                                                      Rubber Side   1.6    2.4                                          500%        Chrome Side   2.2    3.0                                                      Rubber Side   1.6    1.8                                          ______________________________________                                    

The various modifications and alterations of this invention will beapparent to those skilled in the art without departing from the scopeand spirit of this invention, and this invention should not berestricted to that set forth herein for illustrative purposes.

We claim:
 1. A multi-layer film laminate comprising at least onenonelastomeric skin film layer and at least one core film layer, the atleast one skin film layer and the at least one core film layer togetherforming at least one preferential activation zone where the filmlaminate will preferentially elongate when stretched, wherein said atleast one core film layer is substantially elastomeric, each of saidcore and skin layers being substantially coextensive and havingrelatively constant average thicknesses over both the at least onepreferential activation zone and an at least one adjacentnon-preferential activation zone such that, for a given skin or corelayer, the skin or core layer thickness in one zone will besubstantially the same as the same skin or core layer thickness in allzones, said at least one skin film layer and/or at least one core filmlayer are provided such that when the multi-layer laminate is stretchedsaid at least one preferential activation zone will preferentiallyelongate and can recover in said preferential activation zone to becomean elastic zone, of said multi-layer film laminate, and adjacentmulti-layer non-preferential activation zones will not preferentiallyelongate to provide substantially inelastic zones.
 2. The elastomericfilm laminate of claim 1 wherein said at least one preferentialactivation zone has lower relative modulus regions over at least 20% ofits extents on average in the direction transverse to the stretchdirection.
 3. The elastomeric film laminate of claim 2 wherein said atleast one preferential activation zone has lower modulus regions over atleast 50% of its extents on average in the direction transverse to thestretch direction.
 4. The elastomeric film laminate of claim 3 whereinnon-preferentially activated zones comprise a second zone having lowermodulus regions at least 20% less over its extents, on average,transverse to the stretch direction, compared to the comparable extentsof said at least one preferential activation zone.
 5. The elastomericfilm laminate of claim 2 wherein said laminate when stretched willpreferentially elongate the low modulus regions in said preferentialactivation zone past the inelastic deformation limit of at least oneskin layer which layer will form a microtextured surface upon recoveryof the laminate.
 6. The elastomeric film laminate of claim 1 wherein thelaminate in said preferential activation zone will recover from itsstretched length by 15% or more after at least 1 second.
 7. Theelastomeric film laminate of claim 6 wherein the laminate will recoverfrom its stretched length by 15% after at least 5 seconds.
 8. Theelastomeric film laminate of claim 7 wherein the laminate will recoverfrom its stretched length by 15% after at least 20 seconds.
 9. Theelastomeric film laminate of claim 8 wherein the laminate will recoverfrom its stretched length by less than 15% after 20 seconds and whenthen exposed to an activation temperature above 26.7° C. will recover byat least 50% of the total recovery.
 10. The elastomeric film laminate ofclaim 1 wherein the recovery can be initiated mechanically.
 11. Theelastomeric film laminate of claim 1 wherein the laminate recovers by atleast 15% after 1 second.
 12. The elastomeric film laminate of claim 2wherein non-preferentially activated zones contain a relatively highmodulus region that has been subjected to an annealing process.
 13. Theelastomeric film laminate of claim 2 wherein said relatively low modulusregions have been subjected to a plasticization treatment.
 14. Theelastomeric film laminate of claim 2 wherein non-preferentiallyactivated zones contain at least one relatively high modulus region thathas been subjected to a crosslinking treatment.
 15. The elastomeric filmlaminate of claim 4 wherein, in at least one layer, a higher moduluspolymer composition, than the polymer composition of said layer in atleast one low modulus region, is used in said second zone.
 16. Theelastomeric film laminate of claim 15 wherein said higher moduluspolymer composition comprises higher modulus polymer than polymer insaid lower modulus polymer composition.
 17. The elastomeric filmlaminate of claim 15 wherein said higher modulus polymer composition andsaid lower polymer composition are predominately comprised ofsubstantially identical polymers, either or both of which furthercomprising a modulus modifying additive.
 18. The elastomeric filmlaminate of claim 15 wherein said high modulus polymer composition is anonelastomer, and said low modulus polymer composition is an elastomericcomposition in which at least one layer comprises a core layer.
 19. Theelastomeric film laminate of claim 1 wherein at least one of said corelayers is an inner layer and at least one skin layer is an outer layer.20. The elastomeric film laminate of claim 16 comprising at least twoskin layers.
 21. An elastic adhesive tape comprising the elastomericfilm laminate of claim 1 wherein an area outside at least onepreferential activation zone further comprises an adhesive layer. 22.The elastic adhesive tape of claim 21 wherein two non-preferentialactivation zones are adjacent to either side of a preferentialactivation zone wherein adhesive layers on said non-preferentialactivation zones are on the same face of the laminate, which elastictape is of a size suitable for use as an adhesive closure tab.
 23. Theelastic tape of claim 22 comprising a diaper closure tab.
 24. Theelastic tape of claim 21 wherein said preferential activation zonefurther comprises a low adhesive backsize on at least one face thereof.25. The elastomeric film laminate of claim 1 wherein said at least onepreferential activation zone is comprised of at least one preferentialstress region.
 26. The elastomeric film laminate of claim 25 whereinsaid at least one preferential activation zone has preferential stressregions over at least 20% of the laminate extents, on average, in thedirection transverse to the stretch direction.
 27. The elastomeric filmlaminate of claim 26 wherein at least one non-preferential activationzone comprise a second zone having preferential stress regions at least20% less over its extents, on average, transverse to the stretchdirection as compared to the corresponding extents of said at least onepreferential activation zone.
 28. The elastomeric film laminate of claim25 wherein said preferential stress region is formed by scoring,ablating, corona treating or removal of material from at least one layerof said region.
 29. A multi-layer film laminate comprising at least onenonelastomeric skin film layer and at least one core film layer, the atleast one skin layer and the at least one core layer formingpreferential activation regions and non-preferential activation regionsfor a given skin or core layer, the skin or core layer thickness in oneregion will be substantially the same as the same skin or core layerthickness in all regions, wherein said at least one core layer issubstantially elastomeric in said preferential activation regions, andsaid at least one skin layer and/or said at least one core layer areprovided such that when the multi-layer laminate is stretched, saidpreferential activation regions can elongate and recover in theelongated regions to an elastic state.
 30. The elastomeric film laminateof claim 29 wherein said preferential activation regions define zones ofpreferential activation on the laminate.
 31. The elastomeric filmlaminate of claim 30 wherein at least some of said preferential andnon-preferential activation regions form a pattern which when stretchedand recovered will form a patterned surface macrotexture with at leastone microstructured skin layer in said preferential activation regions.32. The elastomeric film laminate of claim 31 wherein both saidpreferential and non-preferential activation regions in said patternstretch and are recovered.
 33. The elastomeric film laminate of claim 32wherein both said preferential and non-preferential activation regionsin said pattern form microstructured skin layer regions.
 34. Theelastomeric film laminate of claim 25 wherein said at least onepreferential stress region has been corona ablated.
 35. The elastomericfilm laminate of claim 25 wherein said at least one preferential stressregion has microcracks created by corona treatment.
 36. The elastomericfilm laminate of claim 29 wherein said preferential activation regionshave been corona ablated.
 37. The elastomeric film laminate of claim 29wherein said preferential activation regions have microcracks formed bycorona treatment.
 38. An article having a film laminate with elasticregions comprising a film laminate having elasticized preferentialactivation zones and nonelasticized non-preferential activation zoneswhich laminate is comprised of at least one nonelastomeric skin filmlayer and at least one at least partially elastomeric core film layersuch that, for a given skin or core layer, the skin or core layerthickness in one zone will be substantially the same as the same skin orcore layer thickness in all zones.
 39. The article of claim 38 whereinsaid article is a garment further comprising an engagement surface towhich the elastomeric laminate is attached.
 40. The article of claim 39wherein said laminate is attached to said engagement surface at saidnonelasticized zones.
 41. The article of claim 39 comprising a diaper.42. The article of claim 41 wherein said laminate comprises a diaperclosure tab comprising a central elasticized zone and two nonelasticizedouter zones at least one of which is adhesive coated on at least oneface thereof.
 43. The article of claim 41 wherein said laminatecomprises an elasticizing element at a leg or waist engaging area and isattached to said engaging surface at said nonelasticized zones.
 44. Thearticle of claim 43 wherein said elastic laminate is attached to saidengaging surface with adhesive, which adhesive was applied as a hot meltthereby defining annealed nonelasticized zones.
 45. The article of claim38 wherein said nonelasticized and elasticized zones extend continuouslyacross substantially entire extents of said laminate.
 46. The article ofclaim 38 comprising nonelasticized and elasticized regions which form apattern with single extents intersecting multiple elasticized andnonelasticized regions within a single overall activated elasticizedzone.
 47. The article of claim 38 wherein said elasticized zones arecomprised predominately of relatively low modulus regions and saidnonelasticized zones are comprised predominately of relatively highmodulus regions.
 48. The article of claim 38 wherein said elasticizedzones are comprised predominately of regions treated to createpreferential stress concentration.
 49. The elastomeric film laminate ofclaim 1 wherein the activated zone width decreases by less than 20% whenrestretched to the extent of permanent deformation of at least onepreviously deformed skin layer.
 50. The elastomeric film laminate ofclaim 1 wherein the surface area formed on the microtextured skin layeris at least 50% greater than an untextured surface.
 51. The elastomericfilm laminate of claim 1 wherein the laminate is a film formed ofsubstantially coextensive layers having relatively constant averagethicknesses across the width of the laminate.
 52. The elastomeric filmlaminate of claim 1 wherein the core and skin layers remain insubstantially continuous contact in the activated zones followingstretching and recovery.
 53. The elastomeric film laminate of claim 1wherein the skin and core layers remain in substantially intermittentcontact in the activated zones following stretching and activation. 54.The film laminate of claim 1 wherein the laminate is capable ofrecovering instantaneously, over time or upon the application of heatdepending on the degree of stretch past the deformation limit of atleast one skin layer in the activation zones.
 55. The elastomeric filmlaminate of claim 1 wherein the at least partially elastomeric corecomprises an A-B-A block copolymer.
 56. The elastomeric film laminate ofclaim 55 wherein the ABA block copolymer comprises astyrene-isoprene-styrene, styrene-butadiene-styrene or styrene-ethylenebutylene-styrene block copolymer.